The Digital StudyHall

Randolph Wang∗ Urvashi Sahni† Sumeet Sobti∗ Nitin Garg∗

Jaswinder Pal Singh∗ Matthew Kam ‡

Arvind Krishnamurthy§ Thomas Anderson¶

Abstract

In this paper, we describe a distance learning systemthat would allow resource-starved village schools inrural India to benefit from the better human and con-tent resources available in the urban environments.The e-learning landscape is littered with misguidedand expensive “wire-the-schools” projects that havelittle to show for in the end. To avoid retracing thesemissteps, we must follow at least two important prin-ciples in our solution: (1) cost realism, which is essen-tial if we were to scale up the system to encompass alarge number of villages, schools, and students in thelong run; and (2) building systems that solve end-to-end education problems, instead of narrowly focusingon just providing connectivity.

The proposed Digital StudyHall system has the fol-lowing novel key components. The first is a genericdigital communication mechanism that places bitson storage media transported by the postal sys-tem instead of wires. This mechanism, the Post-

manet, provides pervasive, high-bandwidth, and low-cost asynchronous connectivity to just about anyplace. When combined with a low-latency channel,such as a packet radio connection, we may combinethe latency and bandwidth advantages of both chan-nels. Robotic arm-based automation in our head-quarters site further enhances transparency and effi-ciency. The second is a mechanism that turns regu-lar TV screens into “networked thin client displays.”

∗Department of Computer Science, Princeton University,{rywang,sobti,nitin,jps}@cs.princeton.edu.

†The StudyHall Foundation, urvashisahni@yahoo.co.uk.‡Department of Electrical Engineering and Com-

puter Science, University of California Berkeley, mat-tkam@cs.berkeley.edu.

§Department of Computer Science, Yale University,arvind@cs.yale.edu.

¶Department of Computer Science and Engineering, Uni-versity of Washington, tom@cs.washington.edu.

This mechanism, which we call EdTV, lowers the costof end user devices, and truly bridges the last mile byleveraging TV and radio control signals. The thirdis a web repository that collects education content,and connects learners and teaching staff across timeand space, so staff in urban schools and volunteers(potentially from overseas) can contribute in a waythat allows them to make flexible time and locationcommitments. This site, dubbed the learning eBay,would be accessible via both conventional networksand the Postmanet. These components would en-able a wide variety of digital education “workflows,”such as lecture capture and replay, homework collec-tion and feedback, and question-answer sessions. Wealso plan to perform pedagogy research on the DigitalStudyHall, so that it can serve as an effective learningscience testbed, tightly combining education researchand practice.

1 Executive Summary

In the past decade, Dr. Urvashi Sahni, a native ofLucknow, India, and a co-author of this paper, hasbeen working on improving basic education for dis-advantaged children in rural areas and urban slumsin her native state. “StudyHall,” a highly regardedschool run by Dr. Sahni in the city of Lucknow, catersto both middle-income students (in regular classes)and girls from the urban slums (in an after-schoolprogram). StudyHall also subsidizes six affiliated vil-lage schools. Like the vast majority of typical ruralIndian schools, these affiliated village schools experi-ence a severe shortage of well-trained teachers.

We would like to build on Dr. Sahni’s previouswork, and construct a “Digital StudyHall” that al-lows resource-starved village schools to benefit fromthe better human and content resources available inthe urban environments. As an initial step, we wouldlike to knit the StudyHall headquarters and the affil-

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iated village schools into a networked cohesive wholeso they can better communicate and systematicallyshare content with each other, so, for example, high-quality lectures digitally captured at the headquar-ters are made available to the village schools, andhomework and questions from the village schools canbe handled by the staff or the volunteers at the head-quarters.

In the longer run, our goal is to scale up the Digi-tal StudyHall to serve a much greater number of ruralstudents, including those living at places that have noschool today, and to allow qualified volunteer teachersbeyond those in Lucknow, including volunteers over-seas, to contribute remotely via the system. Notethat our goal is not to compete against or replacehuman teachers; on the contrary, our goal is to am-plify the reach and power of the limited number ofqualified teachers and volunteers that we do have.

1.1 Guiding Principles

The e-learning landscape is littered with misguidedand expensive “wire-the-schools” projects that havelittle to show for in the end. We do not intend toretrace those missteps. There are a couple of princi-ples that we intend our project to follow. The firstis cost realism. Consider a recent survey of schoolsin Bihar, Madhya Pradesh, Uttar Pradesh, and Ra-jasthan [10], which shows that 63% of the schoolshave leaking roofs, 58% have no drinking water, 89%have no functioning toilet, 27% have no blackboards,and 8% have none of the above! The high cost ofa large-scale conventional “wire-the-schools” attemptmust be carefully weighed against these pressing ba-sic needs. Priority-setting and cost/benefit analysisis crucial [14]. Keeping the per-school expendituredown would allow us to eventually scale up our sys-tem to encompass a greater number of schools andstudents.

The second principle is focus on problem solvingand system building. Providing connectivity is only apart of a solution. Consider the much-touted launchof EDUSAT, India’s first educational satellite placedin orbit in September of 2004. Five months after thelaunch, all the pieces are functioning in space, butthere is virtually no ground support to enable thedelivery of distance education to remote parts of ru-ral India, which was to be the satellite’s chief benefit.Nor are the technology, the content or the trainedmanpower needed to allow the satellite to explore itsfull potential [8]. After a massive initial investment,

the maximum that can be achieved this year is addingto existing learning facilities at a handful of estab-lished national universities. Given the mountainoussupport tasks that still need to be accomplished, andthe fact that EDUSAT’s lifespan is only seven years,it appears that India is unlikely to be able to takefull advantage of the money and effort it has investedin developing and launching the satellite. The lessonis that we need to focus on building whole “systems”that solve end-to-end problems.

1.2 Innovative Claims

The proposed Digital StudyHall is built on top of thefollowing three novel key components.

• The Postmanet exploits digital storage media(such as DVDs) transported by the postal systemas a generic digital communication mechanism. Inessence, under this approach, network packets nor-mally placed on wires are now placed on DVDs in-stead. While the idea of sending digital content viathe postal system is not a new one, none of theexisting attempts (such as Netflix) have turned thepostal system into a truly generic and transparent

communication channel—to fully realize the potentialof this approach, and to transparently scale up thesystem, one essentially needs the analogous equiva-lent of a networking software stack (such as TCP/IP)that manages point-to-point as well as end-to-endtransmission issues (such as the analogy of a “packetloss”).

The Postmanet allows us to have pervasive, high-bandwidth, and low-cost asynchronous connectivityto just about any place, including the remotest ar-eas. Such a high-latency and high-bandwidth chan-nel can also be complemented by a low-latency andlow-bandwidth link, such as a cellular link or a packetradio link, where it is available, so we can combinetheir bandwidth and latency advantages.

In the Digital StudyHall, a key application ofthe Postmanet is a Postmanet-based http (or phttp)mechanism that allows village schools to interact witha web-based content repository housed at the Luc-know headquarters. Under this approach, http re-quests, replies, and server script fragments can beentirely encapsulated on DVDs transported by thepostal system. A robotic arm-operated DVD proces-sor at the headquarters allows us to automate almostall aspects of the phttp operations.

• EdTV allows us to turn regular TVs into “thin

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client displays” driven by a shared computer. Themost immediate benefit of this approach is that itprovides a low-cost solution to the “display problem”in village school classrooms: the problem of not hav-ing enough computer displays for all students to seeclearly.

The implication of the EdTV approach, however,reaches beyond the classroom, both literally and fig-uratively. Any TV sets within the transmission rangeof the inexpensive transmitter powered by the villagecomputer can receive the computer’s display content,and a cheap custom-made radio transmitter allows aTV viewer to beam control commands back to thevillage computer.

This approach solves several difficult problems: itlowers the cost of end user devices, and it trulybridges the last mile by leveraging TV signals inone direction and radio control signals in the other.EdTV opens up a “portal” for interesting computer-based applications into a poor household that wouldhave otherwise been beyond the reach of more con-ventional technologies. (We discuss some of the non-education applications near the end of this paper.)

In a way, EdTV is similar to kiosks. EdTV essen-tially brings a “face” of a kiosk onto each TV screenwithin the transmission range. This allows one to ac-cess services from the convenience of one’s home at atime of one’s choosing, and it allows multiple peoplein front of multiple TV screens to share a collectiveexperience. These are the advantages that kiosks can-not provide.

• The Learning eBay is a site that connects learnersand teaching staff across time and space; this is anal-ogous to how an auction site matches supplies anddemands. Volunteers and professionals all over theworld can contribute content, conduct online teach-ing sessions, grade homework assignments, run vir-tual “office hours” via the site. Students and staffwith limited experience or resource may tap into thissite to augment their learning. Such a site wouldallow volunteers (potentially from overseas) to makeflexible time and location commitments. This site (orthe content repository) will be housed at the head-quarters StudyHall school in Lucknow. People allover the world with conventional network access canaccess the site via the web. People who have no con-ventional network access, or those with limited band-width, including those in the village schools that weserve, access the site via the Postmanet-based http(or phttp) mechanism.

The repository will initially be rapidly populatedwith digital captures of high-quality lectures givenat the headquarters school. Other types of content,which may require more time to develop, will beadded gradually. All these materials will be madeavailable to the village schools via phttp. Villageschools lacking qualified graders may submit theirhomeworks to be graded and receive subsequent feed-back digitally. We will also work with volunteers froma neighboring teacher training institute to improvethe content and the services available through thesite.

These components share a great deal of synergy.The combination of the repository and the Post-manet, namely the phttp-accessible repository, pro-vides an abstraction that is akin to that of a dis-tributed file system: it makes a single name spaceavailable “everywhere,” including those places thatlack conventional networking access, and allows read,write, navigation, and other primitives to be per-formed on this name space. This file system anal-ogy means that the phttp-accessible repository is asufficiently general abstraction that can be used tosupport other applications. The combination of thePostmanet and EdTV also represents a natural two-hop solution: the ubiquitously available Postmanetfeeds the EdTV “base-station” with high-bandwidthcontent at low cost, and EdTV completes the “fi-nal leg” by making available to the households cheapend viewing devices and two-way TV and control sig-nals. And finally, the repository abstraction providesa convenient abstraction to build shared EdTV appli-cations with. A common theme of these componentsis that they allow sharing and the delivery of highlycustomized content and experiences.

All these mechanisms are designed specifically toaddress the two previously mentioned guiding prin-ciples: low cost, and building end-to-end problemsolving systems. For example, the Postmanet is alow-cost but highly effective network; EdTV is a low-cost but highly effective “networked thin client dis-play;” and the homework feedback mechanism usedby the learning eBay, which we discuss in greater de-tail later, minimizes printing so we do not have tospend too much on expensive printer cartridges andprinter papers. We carefully “penny-pinch” on theamount of equipment each village school requires sowe can scale up the system to cover more schools andkids. And instead of narrowly focusing on connectiv-ity, the learning eBay is designed to be a problem-

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solving system that addresses “workflows” such asthose of content capture and delivery, homework feed-back, and question-answer sessions.

Of course, the technologies are only half of thestory of the Digital StudyHall—the other half is ped-agogy research. Past experiences with comparablesystems [6, 5, 1] indicate that instigating interactionswith and among students can significantly improvethe effectiveness of these digital teaching systems.The Digital StudyHall faces unprecedented challengesand opportunities. Many more types of interactionsare possible: asynchronous digital interactions be-tween villages and the headquarters, face-to-face in-teractions between the local village staff and the stu-dents, and those among students. A goal of the ped-agogy research is to devise the most effective meansof conducting these interactions. A key strategy isto encourage students to help each other: such co-operative learning processes can be less intimidating,more personal, and more dynamic than traditionalapproaches, while the digital content provides struc-ture and the local staff ensures discipline.

As we conduct these experiments, we hope to turnthe Digital StudyHall into a learning science testbedthat allows research and practice to be intimately in-tertwined: experiments will be carried out in realisticsettings, and the best pedagogy practices get adoptedquickly and widely.

1.3 Summer Deployment

We are planning to test-deploy a prototype DigitalStudyHall this summer in the Lucknow headquar-ters and the six affiliated village schools. The testdeployment will exercise the content repository, thePostmanet-based http mechanism, the EdTV “net-worked thin client displays,” lecture capture and re-play, and homework feedback workflow. We will workwith and learn from the headquarters staff, villageteachers, volunteers from the teacher training insti-tute, and students to understand how to improve theprototype.

If the prototype turns out to be viable, we will trainthe staff and the volunteers to operate the system, sothat the system can begin to benefit teachers andstudents in their daily work.

Collaborating with the staff, we will design andperform preliminary pedagogy research experiments.These experiments would explore the space of pos-sible ways the system can be used and attempt todiscover the most effective methodologies.

While the above activities will take place in the ex-isting schools, a more ambitious goal in the longer runis to set up schools at places where none exists today.Such a school would have at least a trained staff whooperates the village school equipment and interactsdirectly with school children. The bulk of the teach-ing and learning activities will rely on asynchronousinteractions with the headquarters. An intermedi-ate step to reaching this more challenging goal is toset up digitally-powered higher-grade classes in someof the existing village schools. The vast majority ofthe rural schools offer only classes one through five.The lack of opportunities for affordable education be-yond class five is a serious problem. At places wheresuch opportunities do exist, girls are also more likelyto drop out before they reach these higher grades.During our summer trial deployment, we will set updigitally-powered higher-grade classes for girls in thepremises of some of the existing schools.

Once the communication and device infrastruc-tures are put in place of the villages, these infrastruc-tures have the potential of supporting other types ofapplications and services that may improve the livesof the locals. These may include health care, com-munication, and commerce-related services, which wediscuss near the end of this paper. During our stay,we will study the feasibility of these services in thelocal settings.

The overall objective of the summer deploymentis to learn enough to devise a scale-up plan that en-compasses the technical, pedagogical, and financialrequirements of what it would take to allow more vil-lages, more schools, and more children to benefit fromthe system.

1.4 Questions and Paper Organiza-

tion

In the remainder of this paper, we answer the follow-ing questions:• What are the pressing problems faced by the

StudyHall schools today? How does the DigitalStudyHall compare to current satellite-based ap-proaches? We address these background questionsin Section 2.

• What is the model for connecting remote learn-ers and teachers? We address this question bydiscussing the learning eBay model in Section 3.

• How do we realistically provide connectivity be-tween the StudyHall headquarters (which housesthe centralized repository site) and the many vil-

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lage schools today? We address this question anddiscuss the Postmanet and phttp mechanisms inSections 4 and 5.

• How do we quickly bootstrap the site and pop-ulate it with good teaching content so that thesite may immediately begin to benefit the villageschools? We address this question in Section 6.

• How do we address the “display problem” in acost-effective fashion: the problem of too manykids in a rural school clustered around a singlecomputer display and few can see well? What arethe potential implications of our solution? We ad-dress these questions and discuss the EdTV sys-tem in Section 7.

• How do we digitize homework, transmit it, gradeit, and return feedback to kids, in a cost-effectivefashion? We address this question in Section 8.

• We know we cannot effectively teach kids justby making them watch lessons on TV. Is theresomething fundamentally different here? How dowe provide personalized interaction? We discusssome of the pedagogical research questions in Sec-tion 9.

• Is access to electricity a problem? How do weenvision the Digital StudyHall to be funded in asustainable fashion in the long run? We brieflydiscuss our options in Section 10.

• What are the implications of the infrastructurethat we are putting in place? What other plau-sible synergistic applications and services can beprovided with the same infrastructure? One ofthe motivations for examining some of the poten-tial for-profit applications is the hope that suchapplications could collect revenue to fund the non-profit education and other services. We addressthese questions in Section 11, before we concludein Section 12.

2 Background

2.1 Satellite-Based Approaches

It is useful to compare our approach against satellite-based approaches. Satellite-based approaches are ex-pensive and they require a great deal of support in-frastructure. Satellites are a good broadcast medium:a small number of one-way streams consumed by avast number of content consumers. But broadcastmodels are poor ways of delivering customized con-tent and allowing two-way exchanges. Satellites canalso be used to support non-broadcast or even two-

way communication. If we do that, however, we facea severe bandwidth problem: each of a large numberof communication channels only gets a small fractionof the aggregate bandwidth. The bandwidth limita-tion is especially serious on the uplinks.

One of the important advantages of our approachis that it allows high-bandwidth and any-to-any com-munication, which in turn enables a high degree ofcontent customization and rich two-way exchanges,crucial for applications such as homework collectionand feedback. Indeed, this theme is not limited to thenetworking level—it permeates every aspect of oursystem. For example, the content and schedules ofEdTV “programs” are village-, teacher-, and student-specific. This level of customization is something thatregular broadcast TVs (or satellite TVs) cannot hopeto match. The virtual “market place” of educationcontent and services provided by the learning eBayallows many more other customized interaction op-portunities.

Having noted the differences between our systemand satellite-based approaches, and the fact that thekey components of our system share a great deal ofsynergy, however, we should also point out that com-ponents such as EdTV and the learning eBay are toa large extent orthogonal to the underlying connec-tivity technologies. It is precisely these componentsthat constitute the “whole-system” solution that weneed, the kind of components that EDUSAT lackstoday.

2.2 StudyHall Background

Dr. Urvashi Sahni received her PhD from the Grad-uate School of Education at University of CaliforniaBerkeley in 1994. Dr. Sahni has been widely recog-nized for her efforts to reform education in India andimprove education opportunities for girls [18]. Heraccomplishments include: initiating and managinga school reform project involving 62 schools, 16,000students, and 258 teachers in rural areas of UttarPradesh; launching an innovative in-service programfor the United Nations Children’s Fund (UNICEF)with 30,000 kindergarten and first-grade teachers in28 districts within Uttar Pradesh; working as the di-rector of an action research project to bolster girls’education and serving on the state government’s GirlChild Mission to promote girls’ education; runningthe highly regarded StudyHall school in Lucknow, aswell as operating its affiliated girls’ school and subsi-dized schools in rural areas.

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The StudyHall headquarters school caters to stu-dents from middle-income families. Regular Study-Hall classes run in the morning. The staff at theheadquarters is well trained. The school has earneda reputation for excellence. In the afternoon, theschool premises are used for an after-school programthat Dr. Sahni runs and co-funds. This program tar-gets girls from the urban slums, who would otherwisenot have an opportunity to receive a formal educa-tion. The girls are required to do various householdchores and work in the mornings and evenings, whichis why the after-school program takes place in the af-ternoon hours. In addition to providing a precious ed-ucation opportunity, perhaps more importantly, theafter-school program has achieved a degree of atti-tudinal change: the girls have grown more confidentabout themselves.

The StudyHall headquarters school is also affili-ated with six schools in rural villages, where the con-ditions are much poorer than that at the Lucknowheadquarters. Each school has about 250 students.Low teacher-student ratio is a severe problem: eachschool is staffed by two to six teachers, who are usu-ally not fully qualified to teach the subjects that theyare required to teach. The subjects that the teachersfeel least comfortable with are English, mathematics,and science. The village schools offer classes fromclass one to five, with the exception of one that offersup to class eight, while the headquarters offers classesfrom pre-nursery through pre-college (class twelve).On average, each person of the rural families (and theurban slum families which StudyHall targets) lives onless than $2 per day.

In the summer of 2000, Dr. Sahni started a three-year pilot program exploring the use of computertechnology in her schools. She put together a teamcomprising two government school primary teachers,two recent graduates from the teacher training insti-tute, one ninth grade student, and two Flash soft-ware developers. This team produced science lessonunits in Hindi for classes five through eight. Thesecomputer-based lesson units became integrated intothe curriculum, and teachers began to use the course-ware as a lecturing tool. The shortage of villageschool teachers trained in sciences meant that theselesson units were badly needed. The lesson units alsofacilitated small-team learning: under teacher super-vision, students in small groups helped one anotherto understand the material presented by the course-ware, and senior students made use of the course-ware to help their juniors learn. The pilot program

also helped students gain computer literacy, whichboosted students’ interest in schools, and improvedparents’ enthusiasm of sending their children to theseschools.

The preliminary StudyHall experiences have showna great deal of potential. There are, however, a num-ber of problems that we must address to take Study-Hall to the “next level.” The individual schools arenot part of a connected and cohesive whole system.Lack of physical network connectivity is only part ofthe problem. There is not a system that allows theheadquarters and the village schools, and the villageschools among themselves, to effectively communi-cate and share content. This deficiency prevents thevillage schools from fully exploiting the best humanand content resources in the Lucknow urban environ-ment to address their own shortages. The productionof lesson units, such as the Flash content, is time- andlabor-intensive. We need a faster way of making thehigh-quality lecturing at the headquarters availableto the poorly staffed village schools. Students at theback of village classrooms complained that they couldnot see the computer display at the front. We need acost-effective way of addressing such practical issues.And as we explore the use of technology in such anenvironment, sound pedagogical methodologies mustbe devised to keep up with these developments.

We would like to build on Dr. Sahni’s experiencein working with teachers and children, particularlythose in rural areas and urban slums. Our initialsteps aim at knitting the Lucknow headquarters andthe six village schools into a cohesive whole so thatthe village schools can better benefit from the teach-ing resources in the urban environment. Over time,we would like to scale up the system so that more andmore of the children in rural areas and urban slumscan be brought into the system, enjoying a level of ed-ucation that they could not have gotten otherwise.

3 The Learning eBay

At the center of what we want to build is a site thatconnects learners and teaching staff across time andspace (Figure 1). Volunteers (who may choose towork for free) and professionals (who teach on thesystem for a fee) “plug” themselves into the systemto play various roles. Some may develop teachingmaterials and make them available on the site. Somemay use other people’s materials and conduct teach-ing sessions, either virtually across the network or

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Learning eBay

Learning eBay

Students

Teachers

Graders

Question Answerers

Students

Students

Course materialproducer

Quality assurance

Figure 1: A “learning eBay.”

locally. Some may grade homework assignments thatstudents have submitted to the site; the graded re-sults are available for students to download. Somemay conduct virtual “office hours.” Students andstaff with limited experience or resources may tapinto this online site to enrich or start their localschools. It’s also a way for teachers to get trained.

We dub this site a “learning eBay,” in the sensethat this is a virtual meeting place and a “marketplace” that aggregates and matches “supplies” and“demands,” supplies and demands for educational re-sources and services.

Such a site would allow teaching professionals andvolunteers to make flexible time and location commit-ments: for example, a volunteer can decide to spendperhaps only four hours a week grading some home-work, potentially from his home overseas. This ar-rangement may allow us to address the difficult issueof attracting and retaining well trained and qualifiedteaching staff in remote regions. It may also allow usto build an education system that is analogous to an“open source” model, in which legions of content de-velopers all over the world constantly pool their con-tributions towards a single coherent repository thatis accessible to all. It may also allow parts of the op-erations of a traditional school to be operated basedon an “outsourcing” model: for example, homeworkgrading from villages can be standardized and “out-sourced” to a centralized remote location (at Study-Hall in Lucknow, for example). Such an outsourcingmodel can address staff shortage in remote areas, en-sure uniform and high standards of the outsourcedoperations, increase specialization and efficiency.

4 The Postmanet

To connect the headquarters repository site to the vil-lage schools, we need a connectivity option that workstoday, is relatively inexpensive, and allows us to rela-tively quickly scale up the number of village schools.We have examined several options. Due to the diffi-culty of providing commercially viable cell coveragein sparsely populated rural areas, the tele-density ofcell phone usage in India as of 2003 is only 2.5% [9].Directional 802.11 [2], while promising, is still largelyexperimental, and setup costs such as that needed forthe erection of tall towers (on which parabolic anten-nas can be mounted) are very high. We are plan-ning to use packet radio (ham radio) to provide in-stantaneous but low-bandwidth connectivity betweena village school and the Lucknow headquarters. Totransmit the multimedia educational content in bothdirections, however, we also need a high-bandwidthconnectivity option.

4.1 What Is the Postmanet?

Making high-bandwidth wide-area Internet accesspervasively available to a large rural audience is adaunting challenge. Instead of waiting for the un-certain takeoff of a number of existing and proposedtechnologies, which can be many years away, in arecent SIGCOMM position paper [20], we proposeto turn the existing world-wide postal systems intoa generic digital communication mechanism as digi-tal storage media is transported through the postal“network.” The proposed system is dubbed the Post-

manet.

While specialized solutions (such as those employedby AOL, Netflix, and some researchers working on as-tronomy data [7]) have emerged, they lack two key de-sired properties: generality and transparency: a gen-eral Postmanet should be able to cater to a varietyof applications; and a transparent Postmanet shouldminimize manual handling of the storage media beingtransported. One way of better understanding theimportance of these goals is to consider an imaginaryPostmanet router device (illustrated in Figure 2).

A Postmanet router (or a P-router) is similar to ahome DSL router. Instead of always forcing outgoingdata through a weak wide-area network, however, theP-router writes some of the outgoing data to a mobilestorage media (such as a DVD). The types of stor-age media used may include read-only or read-writeDVDs, flash memory cards, or hard disks. We shall

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LAN

WAN

Figure 2: A Postmanet router.

generally refer to these storage devices as P-disks. Anoutgoing P-disk, after being ejected from a P-router,is picked up by a postman for delivery via the postalsystem. The postman may also drop off an incomingP-disk, whose data appears on a user computer as ifit had arrived from a conventional WAN. Therefore,unlike specialized solutions such as those employedby AOL and Netflix, the Postmanet should providegeneric two-way communication, just as conventionalnetworks do.

The user of a P-router need not manually inspector process the content of a P-disk; the user need notmanually stage or copy data; and the user need notworry about issues such as potential loss or damage ofP-disks in the postal system. Unlike an AOL or Net-flix user, who must know what to do manually withthese application-specific disks, a Postmanet user’sonly direct manual interaction with the P-router islimited to the insertion/removal of P-disks into/fromP-routers. This is analogous to the fact that low-leveldetails such as packets and routers are minimally vis-ible to a conventional network user.

When a P-router user needs to send to multiple re-ceivers, or when multiple applications need to sharethe Postmanet, ideally, it would be desirable if onlya single outgoing P-disk needs to be sent per post-man visit. Similarly, if a P-router user needs to re-ceive from multiple senders, it would be desirableif there is only a single incoming P-disk that con-tains all the incoming data. This is in contrast toad hoc application-specific solutions, which never al-low, for example, AOL and Netflix data to be placedon a single disk. The sharing of a single Post-manet infrastructure by multiple applications andmultiple users is consistent with the multiplexing andde-multiplexing jobs performed by conventional net-works.

The provision of an application-neutral Postmanet“public transit” system that is easily and cheaply ex-ploitable by any potential communicating parties isimportant. This is analogous to the fact that the ex-

isting Internet is such a generic infrastructure. With-out it, a potential innovator who is interested in de-veloping a Netflix-like application may need to rein-vent the whole infrastructure from scratch. The co-existence of multiple Netflix-like infrastructures canlead to various forms of inefficiency. Smaller play-ers may not be able to afford to put up their owninfrastructure at all.

4.2 The Postmanet Advantages

Compared to more conventional wide-area connectiv-ity technologies, the Postmanet enjoys several impor-tant advantages.

• Wide reach. The postal system is a truly global“network” that reaches a far greater percentage ofthe world’s human population. To leverage the postalsystem for digital communication, one needs no sig-nificant new investment in exotic equipment. In In-dia, for example, facilities for daily delivery and clear-ance of mail exist in every village in the country [15].The Postmanet router could be a shared resource thatis deployed in locations such village schools. We alsodiscuss ways of bringing services to individual house-holds in later sections (using the EdTV approaches).

• Great bandwidth potential. While the bandwidthpotential of a “sneaker net” is well known, some mayconsider it to be a temporary fluke stemming fromthe relatively poor capacity of today’s Internet. We,however, believe that this is not necessarily the case,if we examine some fundamental technology trends.Storage density of flash memory and magnetic diskshas been increasing at the annual rate between 60%and 100%, and it is likely to continue in the foresee-able future. This tremendous rate of improvement islikely to be almost directly translatable to the amountof bytes transportable by the postal system for a fixedcost or in a fixed volume. Besides flash memory andhard disks, the next generation Blu-Ray DVDs canhold up to 27 GB per single-layer disc today (and 54GB per dual-layer disc). Sony is planning to commer-cialize a 4-layer 100 GB version in 2007, and it hasalready successfully developed an 8-layer 200 GB ver-sion [13]. Commercially realizable technologies thatwould produce 4-layer 1 TB discs are expected to beavailable around 2010 [19]. One can also ship multipleunits of these storage devices. As better storage de-vices become available, they can be instantaneouslyand incrementally translated into Postmanet band-width improvements.

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In contrast, the wide-area network bandwidthgrowth is constrained by labor-intensive and costlyfactors such as how quickly we can dig ditches tobury fibers in the ground, how quickly we can furnishlast-mile wiring to homes (an endeavor that can beprohibitively expensive), how quickly we can launchsatellites, or how quickly we can erect WiMax (thelonger-distance versions of WiFi) towers. These fac-tors are unlikely to improve faster than the expo-nential growth rate of storage density. Satellite- andWiMax-based solutions may face aggregate band-width limitations. And the future of some of thesealternatives (such as WiMax) is far from certain. Farfrom being a temporary fluke, the bandwidth gap be-tween Postmanet and more conventional alternativesis likely here to stay and, indeed, widen. We do not,however, necessarily view Postmanet as a competitorto these other alternatives. Before better alternativesbecome a widely deployed reality, exploring the Post-manet, an alternative that can already deliver practi-cally infinite bandwidth today, may foster the devel-opment of and demand for sophisticated bandwidth-intensive applications, which may one day readily mi-grate onto alternative connectivity technologies. ThePostmanet can also coexist with other connectivitytechnologies to complement their bandwidth limita-tions.

• Low cost. The goal of providing citizens with af-fordable access to postal service is typically an inte-gral part of most nations’ postal system charters.

• Ease of incremental adoption. A single pair of Post-manet users can already derive useful value from thesystem, without having to wait for a massive-scaleuser community or world-wide infrastructure to de-velop. From this modest start, the system can growgradually. This incremental deployment may circum-vent the classic “chicken-and-egg” problem associatedwith the difficulty of simultaneously developing in-frastructures, applications, and user populations.

4.3 Some Implementation Considera-

tions

The Postmanet has long (but reasonably predictable)latencies. We call such a channel a High LatencyHigh Bandwidth (HLHB) channel. Correspondingly,we call a traditional Internet connection a Low La-tency Low Bandwidth (LLLB) channel. For placesthat have access to both an HLHB channel and an

LLLB channel (such as that enabled by packet radio),an interesting problem is how to exploit an integratedand simultaneous use of both channels to get the bestof both worlds. For example, small requests, acknowl-edgements, “NAKs,” and control messages may besent along the LLLB Internet, while large messagesare staged on mobile storage devices for transmissionby the HLHB postal system.

There are several alternatives that we can use to“route” P-disks from senders to receivers [20]. Ina simple but effective method, well suited for ourinitial StudyHall environment, an end user alwayssends/receives P-disks directly to/from a single datadistribution center (called a P-center). (The P-centerwould be co-located with the StudyHall headquar-ters in Lucknow.) Although any centralized solu-tions have obvious disadvantages, an important ad-vantage of this approach is that each end user han-dles only a single P-disk, regardless how many othersites he communicates with per postman visit: asthe P-center copies data from its incoming P-disks toits outgoing P-disks, it first demultiplexes incomingdata and then re-multiplexes outgoing data, minimiz-ing the number of P-disks handled in both directions.Inexpensive robotic arm-operated, multi-drive DVDwriters that can process about 600 DVDs per day al-ready exist today and they can keep manual laborcost to a minimum.

Among the many potential applications of Post-manet that we have discussed in our position pa-per [20], a most promising one is the delivery of ba-sic education to impoverished rural areas: the widereach, huge bandwidth, and low cost advantages ofthe Postmanet makes it an attractive mechanism fortransmitting multimedia content between StudyHalland the village schools in both directions.

5 phttp: Postmanet-based http

5.1 What Is phttp?

The central repository housed at the StudyHall head-quarters in Lucknow is accessible via the conven-tional Internet so teaching staff and volunteers whohave “normal” web access from either within Indiaor from overseas can contribute to it. To make therepository available via a web interface to isolatedvillage schools, however, requires an unconventionalnetworking approach, and one of the most importantapplications of the Postmanet discussed in the previ-ous section is to deliver web access. Instead of trans-

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mitting web request and reply messages across a wire,in this section, we discuss a system that automati-cally encapsulates these messages entirely on DVDmedia transported by the postal system. We call it“Postmanet-based http,” or phttp.

Under phttp, a staff member operating a villagecomputer can request (pull) content from the repos-itory, and the headquarters staff can push contentto the village schools. They can also perform otheroperations such as search and browse. Note that tosimulate a web experience, we need to handle notonly static data, but also actions that are normallyeffected by scripts and programs executing on webservers. Under phttp, almost all of the DVD-relatedactivities are automated so the users are minimallyaware of them.

The operations of phttp are related to, but alsovery different from, those of “offline web browsing.”An offline web browser eventually gets directly con-nected to the Internet, while a village computer maynever do. Offline browsers can deliver only minimumfunctionality when server-based scripts are involvedin satisfying requests, while under phttp, we explic-itly migrate some code (as well as data) from theserver to the clients so the client browsers continueto function in absence of any conventional connectiv-ity.

We illustrate the operations of phttp using the ex-amples in Figure 3. In panel (a), the repository “pub-lishes” an initial bootstrap DVD destined for eachvillage school. Each bootstrap DVD contains enoughinitial data and a collection of scripts that wouldallow a client to interact with the system withoutany conventional connectivity. Note that the totalamount of the data contained in the repository is farlarger than that can be fit on a DVD so the pur-pose of the bootstrap DVD is just that: bootstrap-ping. We use a robotic arm-operated DVD processorto mass-produce these DVDs so the amount of man-ual intervention is minimum. In this initial step, allthe bootstrapping DVDs may contain identical con-tent; but as we shall see in later steps, in general,the outgoing DVDs produced by the repository sitecontain different content.

In panel (b), a bootstrap DVD arrives at a village,and is inserted into a Postmanet router. Its content isautomatically copied onto the local disk. Upon com-pletion of the copying, the rewritable DVD media isautomatically erased. Again, no manual interventionbeyond inserting the DVD is required.

In panel (c), a staff member at the village interacts

with the computer at a time of her choosing. Enoughdata and scripts from the repository, transported bythe incoming DVD, has been copied to the local harddisk to allow the staff to interact with a subset ofthe full repository site. In our case, for example, anup-to-date version of the full catalog (or “metadata”)of the repository content is always copied to the vil-lage school hard disks to enable browsing and search-ing. Scripts that allow the staff to place “orders” ofchosen repository content, as well as those that al-low the staff to upload selected local content (such asdigitized homework submissions) are also depositedonto the local hard disk. As the staff interacts withthis local view of the site, she may generate variousrequests, including orders (or download requests) ofrepository content and upload requests of local con-tent (such as homework submissions). These requestsare buffered on the local hard disk.

In panel (d), shortly before the the next postmanvisit, the buffered requests on the local hard disk isautomatically burned onto a DVD (which is likelyto be the same rewritable DVD that is erased inpanel (b)). Again, the user is not involved in activi-ties such as file copying: all that is required is remov-ing the DVD from the Postmanet box and handing itto the postal worker.

In panel (e), all the incoming DVDs from the manyvillage schools are collected at the StudyHall andthey form an incoming DVD stack. The roboticarm-operated DVD processor automatically reads thecontent of each incoming DVD onto a hard disk,and erases each incoming DVD, forming a stack ofblank DVDs. Next, the repository machine processesthe requests from each village school (that are nowstored on a local hard disk) and attempts to satisfythem. If the request is for uploading content intothe repository, the data is copied into the repositorydatabase. If the request is for downloading contentfrom the repository, data is copied out of the reposi-tory database and is placed in an outgoing DVD im-age on the local hard disk. At the end of the process-ing, an outgoing DVD image is generated for eachvillage school on a local hard disk.

Now the cycle repeats and we are back topanel (a)—we are ready to generate another stackof outgoing DVDs, using the stack of blank DVDsproduced by the erasure step in panel (e), and theoutgoing DVD images placed on a hard disk (also inpanel (e)). Unlike the outgoing bootstrapping DVDsproduced initially, however, the new stack of outgoingDVDs generated now can contain different content

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outgoingrequests

P-router

incomingDVDs

blankDVDs

robotically-operated DVD processor

outgoingDVDs

blankDVDs

localdisk

repository

(a) (e)

(b) (c) (d)

StudyHall StudyHall

Village Village Village

Figure 3: An example cycle of phttp operations. A key aspect of this process is that there is minimal manual involvement inthe DVD-related operations.

(to satisfy different requests from the village schools).And when these DVDs reach the schools in panel (b),the requested content will be automatically copiedonto the village local hard disks.

5.2 Observations

While the phttp example steps that we have exam-ined in Figure 3 are intuitive, and a savvy computeruser could have done some of this manually, we em-phasize that one of the important aspects of our ap-proach is transparency: almost all of these steps areautomated and not much of the DVD-related oper-ations is visible to end users. This automation andtransparency is important for at least three reasons:(1) if our goal is to scale the digital StudyHall toencompass a large number of schools and students,manual intervention becomes tedious and infeasible;(2) automatic handling of exceptional events, such aslost or damaged DVDs, is also important if we needto scale up; (3) figuring out what scripts to place onDVDs for any particular site is not a trivial task thatordinary users or even site administrators can figureout for themselves—we need a well-defined phttp APIthat “splits” centralized server scripts into pieces thatare distributed at the client and server sites to intelli-gently support asynchronous operations. In additionto their large capacity, low cost, and small weight,the reasons that have compelled us to choose DVDmedia include the fact that we can use commerciallyavailable (and cheap) robotic arm-operated DVD pro-cessors, a crucial part of our automation strategy.

Although our discussion of Figure 3 assumes thatall communication is carried out by transmittingDVDs, as we have discussed in Section 4, a low-bandwidth packet radio link, if available, for example,

can be used to complement the high-bandwidth DVDtransmission. Small data items, such as the catalogof metadata, can be made available on a packet radioconnection, so are small request messages and no-tifications such as receipt acknowledgements, NAKsgenerated as a result of damaged DVDs, and retrans-mission requests.

The discussion in this section has focused on theStudyHall repository application. The phttp ap-proach can be used to support other applications. Forexample, a user may receive a large digital catalog ofAmazon.com on an incoming DVD, browse the cat-alog and place purchase orders that are transmittedback via an outgoing DVD. Or a user may send aGoogle search request and receive a reply DVD thatnot only contains the search result page, but also acrawl of the top-ranked sites. Or we may build avoice/video mail application. An attraction of a gen-eral Postmanet or phttp infrastructure is that all suchapplications may share the same infrastructure and,indeed, the same incoming and outgoing DVDs.

6 Content Capture

Our aim is to quickly populate enough content in therepository so that the village schools consuming thedigital feed from the StudyHall repository may im-mediately start to benefit from it. A critical mass ofinitial content may also provide a good starting pointthat attracts participants to attempt to improve thecontent, with the knowledge that such improvementsmay immediately see practical use. Otherwise, wemight risk the chicken-and-egg problem of having tosimultaneously (and slowly) develop content and at-tract participants. Carefully authored content suchas Flash movies can be very time- and labor-intensive.

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We cannot rely on such content alone as a means ofquickly populating the repository.

Our approach is to record the live lectures at theStudyHall headquarters in Lucknow. The Lucknowschool is taught by a better trained professional staff.Our goal is to allow rural children to receive a levelof education that is comparable to that enjoyed bymiddle-class children in urban areas. Over time, weexpect participants from other places would start tocontribute toward the repository with better and bet-ter content. Of course, we recognize that merely re-playing live lectures in front of rural kids, by itself,is not sufficient. We will address the issues of home-work and interactions in later sections. Nevertheless,capturing and replaying high-quality lectures is stillan important part of a bigger solution.

We will experiment with several different means ofdigital capturing. (1) Real time hardware MPEG4encoders are available (and cheap). The capturedDVD-quality videos are sufficiently compact and harddisks have become sufficiently big and cheap thatwe can realistically capture and permanently storea very large number of lectures and other types ofinteractions in the repository. (2) For content that isshown on computer displays at the Lucknow school,the evolving display content (along with sound inthe environment) can be directly captured on themachine driving the display (using software such asCamStudio). Such content can be potentially cap-tured at higher resolutions, lower frame rates, and/orsmaller file sizes than those of conventional DVD-quality video. (3) We have also built a system thatutilizes a still digital camera: the camera would beprogrammed to release its shutter at a constant rate,and the resulting frames, along with a recorded soundtrack, can be “stitched” together to form a video, avideo that potentially has a very high resolution anda low frame rate. This can be accomplished usingtools such as those based on the “Synchronized Mul-timedia Integration Language” (or SMIL). (4) We willalso store many other types of digital content in therepository. These include digitized homework andfeedback, question and answer sessions, etc. We willdiscuss these issues further in later sections.

Initially, we plan to perform passive capturing,with minimum intrusion on the live sessions. Inthe future, we may experiment with various degreeof teaching staff cooperation, both during and afterthe capture sessions. We will also work with volun-teers from a neighboring teacher training institute.These volunteers can perform various forms of post-

processing to improve the captured content, stagetheir own lectures to be captured, produce feedbacksessions for homework submitted from village schools,and run asynchronous digital question-answer ses-sions. In the process, these volunteers gain exposureto technology and real-life training interacting withvillage students (digitally).

We expect content captured elsewhere will be con-tributed to the repository as well. In the long run,the repository could develop into a peer-to-peer ar-chitecture if there are multiple “centers” of contentaccumulation.

The cost of the equipment needed for the cap-ture activities can be kept very low. Furthermore,although it is critical that we do diligent “penny-pinching” to keep the cost of the per village equip-ment low (because such cost will be scaled up many-fold as we increase the number of schools covered bythe Digital StudyHall), the extra cost incurred onslightly more expensive capture equipment at a smallnumber of centers of teaching excellence should notmatter.

7 EdTV: Thin Client Displays

7.1 What Is EdTV?

One problem that we need to solve with a digitalschool is the “display problem:” the problem of toomany kids clustered in front of a single computer dis-play and few can see well. (Each of the village schoolsaffiliated with StudyHall today, for example, servesabout 250 students, divided into a few classes.) Theobvious solutions have practical problems. Increas-ing the number of displays is costly. Projectors areboth too expensive and too power-hungry. In orderto scale up the Digital StudyHall to eventually en-compass a large number of schools and students, itis critical that we use only cost-effective solutions inthe village schools.

Our solution is (partially) shown in Figure 4. Agraphics card capable of outputting RCA video sig-nal is installed in the village computer. The analogvideo signal is sent to a small TV transmitter. Anumber of regular TV sets are placed in the class-room, each of which receives the air signal comingfrom the transmitter, and displays the village com-puter display content on the TV screen. Only a smallnumber of students need to huddle in front of eachTV screen, which essentially acts as a computer dis-play.

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Lucknow server

TV

ham transmittervillage computer

village

TV transmitteroutput signal

input signal

ham receiver

Figure 4: EdTV.

This solution is inexpensive. The graphics cardcosts $12. The TV signal transmitter costs $37. Indiahas a very healthy used TV market and TV sets canbe had cheaply too. This solution is also energy-friendly. Twelve-inch sets consume as little as 20 W ,far lower than that consumed by almost all laptops,and a projector can consume ten times or more.

Under this arrangement, the TV sets do not needto be inside the village classroom to work: TV setsanywhere in the village within the transmission rangeof our transmitter can receive the display signal aswell. Energy permitting, we can broadcast beyondthe classroom far past regular school hours, so forexample, a kid who misses a school day due to workduring the day can schedule time slots on the trans-mitter at night to catch up. (A recent survey of someof the StudyHall village schools, for example, showsattendance levels of 50% during mango-picking sea-son.) There are many other ways we can use the sys-tem, including homework feedback sessions and otherpotential applications. We can also introduce “input”devices that allow viewers to interact with the system.We will discuss these issues in later sections. We callthese local TV “networks” EdTV.

7.2 EdTV Is Not TV

It is worth noting that despite its initial promise as aneducation tool, TVs have not had the best reputationserving educational purposes. We would like to pointout that EdTV is not TV. We say this for two typesof reasons. First, from a pedagogy standpoint, wewill experiment with various types of personal inter-actions that we discuss in later sections. Second, froma device architecture standpoint, the EdTV screensare more similar to “thin client displays” than regularTVs. We now discuss this distinction.

Regular TVs are “mass media devices”—a verysmall number of content producers dictate what and

when a large number of content consumers watch.Computer displays are exactly the opposite—they are“personal media devices:” they allow many-to-manycommunication, which can carry highly customizedcontent and can occur at flexible times of the com-municators’ choosing. EdTV may not be as “per-sonal” as regular computer displays that we know,and it occupies an interesting compromise point inbetween, but it is probably in spirit much closer tothe “personal media device” end, allowing, for ex-ample, village-, teacher-, and student-specific contentcustomizations that “mass media devices” are utterlyincapable of. The homework feedback sessions thatwe discuss in the next section are an example of suchcustomizations.

7.3 EdTV Is Not WebTV

In some sense, the EdTV approach is similar to thattaken by WebTV: both attempt to leverage an ex-isting large install base of legacy devices and an ap-pliance usage metaphor that people are familiar andcomfortable with to deliver new applications and newservices. EdTV is not as personal as WebTV, andit is not meant to support the existing web expe-rience directly, but it has some important advan-tages compared to WebTV if we choose and designour applications carefully. EdTV does not requirea dedicated per TV conventional network connec-tion. The hardware requirements at the consumerend are minimal (and we discuss cheap “input” al-ternatives later). EdTV has no setup requirementsat an end users’ end and the usage metaphor wouldbe simpler. And if the village computer poweringthe EdTV transmitter is backed by a Postmanet con-nection (either wholly or partially, complemented bya low-bandwidth modem), the shared “backend net-work” would be bandwidth-rich, cheap, and perva-sively available today. And these backend networkadvantages are passed onto the end EdTV users.

Past experiences with Information and Communi-cation Technology (ICT) projects in developing coun-tries have concluded that finding ways of “aggregat-ing demand” is an important strategy of bringing ICTservices to low-income people in a cost-effective fash-ion [14]. Another lesson is that innovative ways ofcombining “old media” with new technologies can beeffective. One example is the Sri Lankan KothmaleCommunity Radio, where villagers use cell phones tocall a live radio station operator, who would look upthe requested information on the web in real time,

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and broadcast verbally the answers over the radiowave to a local community.

The EdTV approach is consistent with theselessons. What is shown in Figure 4 is a three-tieredsystem. The bottom tier, the TV sets (with pos-sible addition of some input means that we discusslater), consists of cheap, specialized and simple de-vices, combining metaphors of both old and new me-dia. The shared middle tier, the village computers,is somewhat more expensive, more general, and morecapable. An important function of this middle tier isto aggregate demand. The data temporarily storedin this layer is potentially expendable. The top tier,the Lucknow server, is more professionally managed,and contains the reliable and ultimate “truth” in itsrepository.

It is also interesting to compare the EdTV and con-ventional kiosk approaches, both of which allow endusers to share relatively expensive computer and con-nectivity resources. EdTV has two significant advan-tages compared to kiosks. First, EdTV allows one toaccess services from the convenience of one’s home ata time of one’s choosing. One may still get a “busysignal” but that is a price of sharing. Second, EdTVallows multiple people in front of multiple TV screensto share a collective experience. Such an experiencecan be more compelling if the application is specifi-cally designed to support this mode of sharing. Onesuch example is a specially designed auction program.(See Section 11.3.) Lack of privacy is a potential issuewith the single-user EdTV scenarios, but the multi-user scenarios in fact exploit it to provide unique andinteresting sharing experiences.

7.4 Extensions

We now discuss several extensions to the basic EdTVsetup. The transmitters that we are looking at haveranges between 500 feet and several miles. To extendthe range when necessary, we may build cheap signalrepeaters of our own, by gluing additional transmit-ters with used VCRs. (Only the TV receiver parts ofthe VCRs are needed for our purpose.)

Another useful extension is providing the end TVwatchers with means of sending input to the villagecomputer. As shown in Figure 4, an inexpensivecustom-made ham radio transmitter acts as a “TVremote,” whose commands are picked up by a hamradio receiver, which is in turn connected to the vil-lage computer. (The same ham radio receiver co-located with the village computer can handle both

communication with the Lucknow server and com-mands from the EdTV input devices.) We may alsouse walkie talkies: a receiver walkie talkie “speak-ing” into the microphone at a village computer run-ning voice command recognition allows end users touse their sender walkie talkies to effect some control.Carefully designed user interfaces would be helpful,especially in shared viewing scenarios. One way oflooking at EdTV is that the output TV signals andthe input radio signals are a way of truly bridging the“last mile.” However, we should not overlook “low-tech” solutions. For example, a human operator mayreplace the role played by the voice recognition soft-ware. Or more simply, a village town hall meetingcan be the setting where the schedule of the localEdTV is determined.

And instead of TV, we can apply a similar ap-proach to radio signal transmission. Certain types ofcurriculum, such as the teaching of spoken English,can benefit from an audio-only approach. Songs sungby local kids in schools could be attractive radio con-tent: past experiences suggest that such elective art-related programs, when introduced to otherwise dulldaily routines in primary schools, can play a signif-icant role raising interest and satisfaction levels inschools.

In later sections, we discuss how we perform cus-tomized educational interactions, such as providinghomework feedback, over EdTV. We also speculateabout other non-educational applications that onemay run over EdTV.

8 Homework Feedback

8.1 The Digital Homework Workflow

Our aim is to scale up the Digital StudyHall so thatit provides digital feeds to many rural schools thathave minimum experienced staff resources. Such aschool may be staffed by a computer operator whoreceives some training from the StudyHall but mayhave otherwise little domain-specific expertise in thesubjects taught at the school. Obviously, playing thelectures recorded elsewhere is not sufficient. Handlinghomework feedback well is important if we were tomake such schools work. We discuss other forms ofinteraction in the next section.

An important principle we need to observe in ourhomework solution is, again, low cost, a necessaryrequirement if we were to scale up the number ofthese schools. Due to the high cost of ink cartridges

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and printer paper, for example, we are shying awayfrom solutions that require a large amount of print-ing. Instead, we will experiment with the followingdigital “workflow.” As we discuss later, this processis designed not only to provide to rural children acomparable homework experience as those receivedby their urban middle-class peers, but also in fact topotentially exceed the quality level of the “normal”homework feedback process that we are familiar withtoday, while also keeping the cost down.

• Digitizing. School children still do homework theway they used to: using pencils and paper. (Lower-quality “non-computer” papers are cheap.) Eachschool is equipped with a digital camera, which eitherthe staff or the students use to digitize the writtenhomework. (We choose to use digital cameras insteadof scanners due to the cameras’ speed, versatility,portability, and simpler power requirements.) Eachschool is also equipped with a microphone, which canbe used to digitize voice. A webcam can be used torecord video to add a more personal touch in certaintypes of interactions and generally enhance interestlevels, but it is not strictly necessary. All this acces-sory equipment should be inexpensive.

• Transmission. The digitized homework is “up-loaded” into the repository by the village staff us-ing the phttp mechanism described in Section 5.Phttp is in some sense an ideal transport for our pur-pose because (1) homework submission and feedbackare intrinsically asynchronous processes, and (2) thetremendous bandwidth potential of phttp allows us agreat deal of flexibility in terms of the type and con-tent of homework and feedback that we can trans-mit: we are free to use all manners of multimediacontent that can provide good end user experiences(experiences that kids are either already familiar withor experiences that are engaging) without worryingabout over-taxing communication links or incurringhigh per-byte cost; one is unlikely to match these ad-vantages using other communication means.

• Grading. As part of the phttp mechanism, therobotic arm-operated DVD processor at the Luc-know headquarters automatically uploads the incom-ing homework submissions into the repository. Thegrader staff (or volunteers elsewhere) downloads thesubmission at a time of their choosing. A grader loadsthe homework into a batch image management soft-ware and uses a tablet pen to scribble on the home-work submission.

In addition to this “written” feedback, a graderalso prepares a video feedback, which is producedby a screen capture process (using software such asCamStudio), as the grader scrolls through the gradedhomework and speaks into the microphone to providea verbal soundtrack. A teaching assistant of an in-troductory Princeton CS course has been using thisprocess to grade homework, and we have found theprocess to be quite natural to use.

In the context of the Digital StudyHall, we plan toproduce two types of homework feedback: collective

and individual. Collective feedback is a video that awhole class views together, and is designed to coverissues such as common mistakes. Individual feedbackprovides more personalized help, especially for thekids who appear to be having trouble. The distinc-tion between these two types of feedback allows us toreduce the total length of the feedback sessions.

The hardware needs of a grader is also minimum:an inexpensive tablet pen and a microphone are allthat is needed. (The video is produced via screencapture so there is no camera involved.) The modestequipment needs make it easier to scale up the num-ber of graders in urban centers such as the LucknowStudyHall headquarters, and also make it easier forindividual volunteers elsewhere to join in and help.

When done, the grader uploads the graded home-work, along with extra feedback files (such as videofiles), back into the repository. This is likely donewith the high-bandwidth local area network at theLucknow headquarters, or a conventional wide-areanetwork if the grader is an outside volunteer. It isalso possible, however, that a grader is located ata bandwidth-starved location, so she could use thephttp mechanism to interact with the repository justlike a village school staff does. In all cases, the graderinstructs the repository to push (again, via phttp) thehomework feedback to the village schools that sub-mitted the homework.

• Feedback. When the graded homework and feed-back arrives at the village school over phttp, data isautomatically copied onto the local hard disk. At atime of her choosing, the staff goes over the homeworkfeedback with her students. The collective feedbackvideo may be played over EdTV to all students inthe classroom. The individual feedback video for astudent may be scheduled to be played at a time ofthe student’s convenience, either in front of the com-puter display, or on an EdTV screen at or near thestudent’s home after regular school hours. The stu-

15

dent may borrow a walkie talkie as an input device,which allows her to pause, rewind, zoom in, or per-form other operations to the content being deliveredover EdTV.

If necessary, the staff or the student may choose toreview some raw images of the graded homework. Ifthe number of students is large, we may increase thenumber of EdTV channels by equipping the villagecomputer with additional RCA signal-capable graph-ics cards and transmitters, at the cost of about $50per additional channel. Homework feedback is an ex-ample application of EdTV that showcases our con-tention that EdTV is not TV: it allows customizedcontent and customized control that is impossiblewith “mass media devices.”

Although we anticipate using EdTV to provide alarge fraction of the feedback, we do not necessarilyrule out other means. Printing out some content, aslong as the scale of printing is not massive, is perfectlyfine. “Answer books,” printed on cheaper papers,like textbooks, could be shipped from the StudyHallheadquarters in advance, kept by the village staff, andprovided to students when needed. This combinationof the low-tech and the high-tech is a theme of theapproach that we are taking to maximize communi-cation effectiveness while minimizing cost.

8.2 Observations and Implications

Having described the remote homework feedback pro-cess, we now make some additional observationsabout the process. Despite the fact that the rural vil-lages may not be staffed by teachers or graders withmuch domain-specific expertise, the homework feed-back experience received by students could in fact bepotentially better than that received by middle-classstudents today: the video feedback sessions, for ex-ample, can be easily and cheaply made and providea much richer and personal learning experience.

The process that we have described is useful notonly for doing homework, but also useful for otherinteractions in general, such as less structured ques-tion and answer sessions. (Of course, this is not asgood as conventional real-time video conference ses-sions; the asynchronous interaction may neverthelessstill prove valuable.)

All the feedback materials are permanently storedin the repository so they can be reused. Some ofthe reuse scenarios allow us to partially overcomethe phttp delay problem. For example, a local staff

could play a good previously recorded feedback ses-sion (potentially made for other students elsewhere)almost immediately after the homework submissionof the current class is made. More personalized feed-back for the current class would come later. So thefeedback a student receives includes both instanta-neous feedback (although the feedback is not terri-bly customized) and customized feedback (althoughthe feedback is delayed). More details of how thistradeoff may work can be found in an earlier paperof ours [11]. One may also reuse previously recordedmaterial by selectively mixing and matching snippetswith newly recorded material.

Even for a school that is locally staffed by well-qualified graders, the repository may still prove valu-able. A grader may choose to occasionally downloadand play some of the feedback recorded at other timesor at other places to augment her own feedback ses-sions. The homework graded locally may be digitizedand uploaded into the repository anyhow, so that thiscontent may benefit students at other places or atother times. One of the more radical (but potentiallyvery promising) approaches that we are consideringis to have the best higher-grade students help otherstudents, potentially located elsewhere. Such “coop-erative learning” may not only give us “extra hands,”but may also prove to be a more personal and less in-timidating learning experience for the students. Wediscuss such approaches more fully in the next sec-tion.

9 Pedagogy and Learning Sci-

ence Research

Although the homework feedback mechanism dis-cussed above allows a fairly sophisticated asyn-chronous interaction mechanism, it is still probablysafe to say that playing the captured lectures alonewill not be sufficient for educating young children. Inthis section, we discuss pedagogy research targetingour Digital StudyHall environment: the staff mem-ber manning a village school may have various degreeof domain-specific knowledge, ranging from none tosomething quite extensive. The question is what wecan do, by utilizing such a staff member, to augmentthe digital feeds to and from the Digital StudyHallheadquarters to make the teaching process in a vil-lage school more effective.

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9.1 The “TVI” Experiences

We draw our inspiration from the “Tutored Video-tape Instruction” (TVI) program conducted at Stan-ford in the 1970s [6]. In the TVI paradigm,minimally-edited videos of unrehearsed lectures areviewed by small groups of students assisted by a fa-

cilitator. The facilitator is not an expert teacher; in-stead, the (simpler) job of the facilitator is to pausethe video tape when questions arise during the playback of the taped lectures. Such questions can beasked by students who are currently viewing the tape,the instructor on the tape, or the students capturedon the tape. During such a pause, the facilitator at-tempts to guide the students toward a resolution ofthe question using a discussion format, before he re-sumes playing the tape. When not many questionsare asked, it is also the facilitator’s job to instigatemore questions and discussions.

Over a number of years, careful studies were per-formed to compare the performance of the studentsparticipating in the TVI program against that ofthree other groups: one was the group of studentsin the live classrooms; the second was the group ofstudents who viewed the lectures live on close-circuitTV and were given the option of interacting with theinstructor using phone hookups; and the third wasthe group of students who viewed the delayed tapedlectures without any augmentation. We call thesethree groups the “live” group, the “interactive TV”(or ITV) group, and the “TV” group, respectively.

While it was not surprising that the TVI groupoutperformed the TV group, what was especially in-teresting was that the TVI group outperformed all

three other groups, including the live group, consis-tently over the years! Indeed, the TVI students ap-peared to lag behind the live (on-campus) students interms of their admission qualifications; yet the TVImechanism appeared to have more than compensatedfor this initial disadvantage.

The conjecture is that there is more systematic in-teraction built into the TVI model than even thatin the live classroom, and this increased amount ofdiscussion in a less inhibiting environment also fos-ters the formation of a group discovery process thatbuilds communication and team skills, all of whichultimately contributing to an enhanced learning pro-cess [12]. Variations of the TVI approach have beentried subsequently [5, 1], and similar degrees of suc-cess are observed.

The TVI experiences point to several important

principles that are highly relevant to our DigitalStudyHall. (1) Although not sufficient by itself,good captured content, when replayed, can be a keyfoundation upon which a digital school curriculumis based. (2) Systematically instigating interactionwith and among students can effectively complementthe previously recorded material and significantly en-hance the effectiveness of the learning process. (3)Successful instigations of interactions can be effectedby relatively simple means (such as a non-expert fa-cilitator pressing the pause button) without necessar-ily requiring a sophisticated, time-consuming and ex-pensive content authoring process. (4) Group learn-ing can play a key role, especially in an environmentwhere the local staff expertise is limited.

9.2 TVI and the Digital StudyHall

Compared to the TVI environment, the DigitalStudyHall faces some very different challenges andopportunities. An obvious challenge is the fact thatthe students we have in the Digital StudyHall areyoung children, and unstructured discussion may notbe best suited for this audience or for the types ofthe subject matters covered. On the other hand, thetechnologies available to us today have advanced farbeyond the VHS tapes and the pause button: digitaltechnologies potentially can allow far more sophisti-cated options than pause-and-resume. Yet, opportu-nities afforded by the digital technologies have yet tobe fully explored.

Having said that, we recognize that the originalpause-and-discuss TVI model has very important ad-vantages: it is simple—it minimizes the amount ofpotential intrusion on the original lectures; it requiresalmost no post-processing of the recorded material;and a facilitator has a relatively simple task. Whileit is important to strive to preserve these advan-tages, we also recognize that there may be a “gradi-ent:” while the original TVI model lies at one end ofthe spectrum in terms of minimizing intrusion, post-processing, and facilitator options, increasing levelsof sophistication along this spectrum may still beworth exploring. We are helped in these explorationsby a skilled and cooperative StudyHall headquartersteaching staff (who may not only tolerate some de-gree of intrusive changes of their normal teaching rou-tine, but indeed also be eager to experiment with andembrace the new technologies), a digital repositorythat collects all teaching materials and encouragesincremental tinkering and experimentation (so post-

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processing efforts of the captured content across timeand space can be harvested and preserved), and a vil-lage school local staff who may have different degreesof expertise and skill (so they can “facilitate” in waysbeyond pause-and-resume).

We now hypothesize some example types of insti-gations of interactions that may play similar rolesas that played by the pause-and-discuss format inthe TVI model, but are potentially more appropriatefor our target audience and course subjects. A five-minute in-class quiz, for example, can be built intoeach lecture conducted at the headquarters site. Thesubsequent live grading and feedback are capturedalong with the lecture. When this lecture is replayedin a village school at a later time, the same quiz is ad-ministered, and the previously captured grading andfeedback session can serve the role of the discussioninstigations in the original TVI model.

The homework feedback sessions, as discussed inSection 8, are also examples of instigating interac-tions. As discussed in Section 8.2, such feedback ses-sions may consist of instantaneous feedback (basedon previously recorded material) or delayed feedback(based on tailor-made material for the specific stu-dents). The same homework feedback mechanism canalso be used to conduct less structured question-and-answer sessions with the remote teaching staff at theLucknow headquarters. What can make these inter-action sessions more useful, in the context of the TVImodel, is to carefully interleave and integrate theminto the flow of lecture playbacks.

Yet another possible type of interaction that wecan conduct in the Digital StudyHall is based on therecognition that the local facilitator, though possi-bly lacking domain-specific knowledge, is far betterat certain tasks, such as pattern recognition, thanany artificial intelligence program. A challenge is todesign content streams that incorporate the facilita-tor intelligence as part of the “system.” For exam-ple, the content stream can instruct the facilitator toidentify certain patterns in students’ verbal or writ-ten responses and choose a corresponding followupcontent snippet to play.

In all these interactions, just like in the TVI model,one of our goals is to encourage students to help stu-dents. In our teaching experiences, we have oftenseen some of the best-performing students emergingas “leaders,” helping their peers learn. Such coop-erative learning processes can be less intimidating,more personal, and more dynamic than that with au-thoritative figures. An important task of the facil-

itator is to foster the formation of a positive groupdynamic that is conducive to cooperative learning.Indeed, we will explore employing the best upper-classmen as facilitators or “facilitator assistants” inlower-grade classes. We will also explore encourag-ing student interactions across the wide area (suchas those between urban students and rural students);their different perspectives may further enhance thelearning experience.

While encouraging group learning is important, wealso recognize that we need to provide structure andensure sound resolutions, so in simple cases, for exam-ple, the framing questions and correct answers wouldbe provided in the pre-recorded content stream, min-imizing digressions during these group interactions.We also note that the types of interactions that wehave discussed are only some examples: they are notmeant to be exhaustive, and only through rigorousevaluation (which we discuss next) can we know theireffectiveness.

9.3 A Learning Science Testbed

Education experts have long lamented the severe dis-connect between research and practice: it is difficultto perform learning science research in realistic set-tings; and it is even more difficult to have researchresults adopted by front-line teachers working in thetrenches [4]. The Digital StudyHall presents a uniqueand efficient testbed that allows research and practiceto be intimately intertwined in an ongoing basis.

For example, a reputable researcher can design ex-periments for evaluating the effectiveness of the dif-ferent instigation methods under the TVI model (dis-cussed in the last subsection) by providing several dif-ferent digital feeds and different instructions for thefacilitators. These digital feeds will be pushed to thetest schools and success metrics (such as in-class quizscores) are gathered. Methodologies that do not workare identified and they are either discarded or furtherimproved. Methodologies that prove successful wouldbecome more widely adopted as the correspondingdigital feeds are picked up by subsequent teachingsessions. Further improvements to these superior dig-ital feeds can be made over time, potentially by otherpractitioners. The content in the repository, like someon the web (to some extent), is self-selecting: the bestgets better and gets used more often. In some sense,the system has memory.

Our hope is that the Digital StudyHall not onlyallows learning science experiments to be easily con-

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ducted in realistic settings, but also “short-circuits”the research-to-practice turnaround time so that thebest pedagogy ideas get adopted quickly and widely.

10 Other Issues

10.1 Electricity

The six village schools currently affiliated with Study-Hall all have access to electricity. (One uses solarpanels, while the rest have either intermittent or sta-ble access to the grid.) In India, however, 40% of thehouseholds, and 60% of the rural households do nothave access to electricity. Although access to electric-ity is not a main issue for our summer deployment, itwill pose a challenge in the longer run as we attemptto bring more schools into the Digital StudyHall sys-tem.

For sites that have no access to electricity today, wehave to rely on one of two solutions. One is to installa solar system, which costs $600 or higher. The sec-ond is to rely on car batteries, which are periodicallybrought back to towns to have them charged. This isa solution that some villagers are already using todayto power their TV sets. We will investigate a mini-mal hardware setup for a village school powered bycar batteries so we can make the most out of them.

10.2 Funding

One question we are often asked is how we envisionthe Digital StudyHall will be funded in a sustainablefashion in the long run. We see four stages (or op-tions). In the initial research and development stage,we will need support from grants and donations fromNGOs and corporations. Beyond this initial stage, wespeculate that we may be supported by three possiblesources. The first is an “open source” model, whichrelies on a legion of distributed volunteers to maintainand improve the system. The second is local govern-ment support. Once we are able to demonstrate thatthe Digital StudyHall is a cost-effective approach todelivering basic education, and that a highly qualifiedteaching staff can have a bigger impact when workingas a part of the system, rational government decisionmakers may choose to spend some of their educationbudget on such a system. Indeed, ideally, we wouldlike to turn over the operation of the Digital Study-Hall entirely to a local staff as soon as it matures.The third potential source is revenue collected from

for-profit applications and services “spun off” dur-ing the process of the Digital StudyHall development.These are the types of applications that can leveragethe same hardware and software infrastructure. Rev-enue collected from users of such applications maybe used to “cross-subsidize” the non-profit educationcomponent. We discuss some of these hypotheticalapplications in the next section.

11 Other Applications

Several key components of the Digital StudyHallinfrastructure that we have described in preced-ing sections have implications beyond the educationapplications—other potentially compelling applica-tions or services may leverage these components aswell. These components include:

• The Postmanet and the phttp communication

mechanisms. This is one of the key enabling com-ponents that allows us to have pervasive, high-bandwidth, and low-cost asynchronous connectiv-ity to just about any place, including the remotestareas. (See Sections 4 and 5.)

• The phttp-accessible content repository. The con-tent repository is a simple abstraction that al-lows operations such as upload, download, pull,push, browse, and search. In addition to theconventional web interface, we also make theseoperations available via phttp. And a roboticarm-operated DVD processor co-located with therepository site allows us to automate almost allaspects of the phttp operations. As we shall see,the content repository is a sufficiently general andpowerful abstraction, upon which other more spe-cific applications can be built. (See Section 5for the phttp operations on the repository andSection 8 for an example of how people interactthrough the repository.)

• The EdTV thin client displays. The EdTV ap-proach allows us to leverage a large install baseof legacy devices, namely TVs, and turn theminto thin client displays powered by a shared com-puter. This approach solves several difficult prob-lems: it lowers the cost of end user devices, and ittruly bridges the last mile by leveraging TV sig-nals in one direction and input mechanisms suchas radio control signals in the other. EdTV opensup a “portal” for interesting computer-based ap-plications into a poor household that would haveotherwise been beyond the reach of more conven-

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tional technologies. (See Section 7 for the EdTVmechanisms and Section 8 for an example of howpeople use EdTV).

In this section, we discuss several hypothetical ap-plications that can be built on top of some or all ofthe above key components. These applications fallinto two categories. One includes non-profit services,such as the “health care eBay” that we discuss next,which happen to share a great deal of synergy withthe “learning eBay” service that we have discussedso far, in terms of both their infrastructural needsand philosophy. The second category includes appli-cations that may be potentially commercially viable.One of the reasons why such applications interest usis the potential of such applications’ generating rev-enue that can be used to fund the non-profit services,making them more sustainable.

11.1 The Health Care eBay

Efforts of improving rural health care face many sim-ilar challenges as those faced by providing good pri-mary education: lack of well-trained professionalsworking and living in remote areas, a severe com-munication barrier due to the difficulty of provid-ing pervasive connectivity, and the requirement forcost-effective solutions. Cost realism is especially im-portant in a resource-limited environment where onemust face the stark tradeoff between, for example,more medicine versus better communication. Thiswas perhaps best illustrated by Bill Gates’ unequiv-ocal declaration at one time that “poor people needmedicine and not computers.”

In reality, however, this choice is more nuanced andis not necessarily a zero-sum game. The old truism,“an ounce of prevention is worth a pound of cure,”has a proven track record, as numerous experienceshave shown that systematic availability of preventivecare and early intervention can significantly reducethe overall cost of the health care system. No less aspokesman that the president of the National Hospi-tal Association made a statement in a national inter-view that prevention is going to be the important fo-cus of health care. The trick is to find a “sweet spot,”where a relatively inexpensive investment in an ef-fective communication and interaction infrastructurecan enable (and, indeed, encourage) the poor to pro-actively seek information and early care.

11.1.1 What Is the Health Care eBay?

In Section 3, we discussed the metaphor of a “learningeBay,” a site that connects teachers and students,and “supplies” and “demands” for education servicesacross space and time. In this subsection, we discuss asimilar metaphor applied to health care, which we calla “health care eBay.” On the health care eBay, fourmain groups of people “meet” virtually: the patients,the local allied care providers, the remote volunteerdoctors, and the medical companies that may providemedicines and supplies.

At least in the beginning stages, we envision thehealth care eBay to be more of an information deliv-ery mechanism than a remote diagnosis system. Alarge fraction of the health care problems in ruralareas, such as those related to malnutrition, vacci-nation, access to clean water, care of infants, can beprevented if the villagers had proper access to rele-vant information. The problem with traditional in-formation delivery mechanisms, such as pamphlets,is lack of means of interaction and lack of pinpointrelevance: one is more likely to ask a question thataddresses an immediate and specific concern or needthan is to read a generic pamphlet.

In the health care eBay, villagers go to a nearbyvillage clinic (which is manned by a staff who oper-ates the equipment, and is analogous to the villageschools discussed in previous sections) to seek healthcare advice. Digitized voice can be helpful for record-ing conversations (especially with illiterate patients).Digital images can be useful for documenting exter-nally visible symptoms. Digital video can be use-ful for documenting motion-related symptoms. Othertypes of inexpensive and simple diagnostic equipmentmay also be used. The staff performs data entry and“uploads” all the patient information into the repos-itory in a way analogous to how homework submis-sions are made (described in Section 8).

Qualified medical professionals, including thoseoverseas, volunteer their time and gain access tothe repository in a way similar to how homeworkgraders use the repository (also described in Sec-tion 8). (Translation of the recorded voice contentcan be done by third party translators via the reposi-tory as well.) The medical professionals may browse,search, or prioritize the cases that they can help with.They may provide advices, refer cases to other doc-tors, request more information, or provide more spe-cific instructions to the local staff. Of course, insome cases, the patients must be instructed to go to a

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more conventional hospital to seek further diagnosisor treatment.

We may complement the high-bandwidth but asyn-chronous Postmanet communication mechanism witha low-latency synchronous communication link, suchas a cellular phone, or one built on top of packet radio.One possibility is to use the Postmanet to upload theinitial bulk data into the repository, establish contactwith a remote medical professional who is willing toexamine the case, and make an “appointment.” Atthe appointed hour, the villager and the remote doc-tor may then communicate with each other using asynchronous voice communication channel. Alterna-tively, a patient may seek initial diagnosis or treat-ment at a conventional hospital, but communicatewith care providers on the health care eBay for fol-lowups.

Although we primarily envision the professionals tobe volunteers, we do not rule out for-profit models,and there may be multiple ways of how the medi-cal professionals may collect some fee. For example,donors may “play” on the site as well. Similarly, med-ical companies may donate (or provide at a low cost)medicines and supplies to the site, some of which maybe shipped to the village clinics, where the local staffis responsible for dispensing them.

Of course, stringent security, privacy, and anti-fraud mechanisms must be built into such a system.For example, patients must obtain services from thesystem only through the screened and trained localstaff, with whom we establish a degree of trust, so, forinstance, it would be harder for fraudulent patientsto fake illnesses and steal free medicines. And onlyreputable doctors and medicine suppliers are allowedto provide services.

Another way the system can help is to dissemi-nate medical information, such as medical journalsand drug information (including dosage information,side effects, and drug interactions) to front-line healthcare providers. Such information is updated fre-quently as new drugs and new discoveries are madeavailable. Timely access to such information is badlyneeded by front-line health care professionals.

11.1.2 What’s New?

Tele-medicine or remote diagnosis in rural areas, suchas utilizing high-resolution digital cameras and satel-lite links to perform retina scans [16], has begun toshow promise in recent years. Doctors in the U.S.are also increasingly utilizing emails to communicate

with their patients [17]. These trends, to a certainextent, help us believe that the health care eBay ap-proach discussed here might indeed work. In addi-tion to the potential shown in previous exercises, thehealth care eBay has several unique features.

• A pervasive communication mechanism. The dig-ital communication provided by the Postmanetand phttp, upon which the rest of the system isbuilt, allows the system to reach practically every-one everywhere. This is an advantage that con-ventional connectivity technologies are unlikely tobe able to match any time soon.

• A cheap and high-bandwidth communication

mechanism. The Postmanet and phttp mech-anisms allow us to transmit practically infiniteamount of image, voice, video, and other typesof medical data virtually for free. This is anotheradvantage that other connectivity options cannotprovide.

• A globally accessible “clearinghouse” that matches

“supplies” and “demands” for health care ser-

vices. Such an eBay-like clearinghouse for healthcare does not exist today. A place that aggre-gates supplies and demands for health care ser-vices across time and space can allow doctors tocontribute in a manner that is flexible in terms oftheir time and location commitments. It gives awhole new meaning to the phrase “doctors with-out borders.” It also helps increase specializationand efficiency.

The health care eBay and the education system (orthe learning eBay) that we are working on share agreat deal of synergy. The software and hardware in-frastructures that we have discussed in previous sec-tions, such as the robotic arm-operated DVD proces-sor, crucial for the automation of the repository op-erations, can be leveraged by both applications. In-deed, it is conceivable that in some locations, the vil-lage school and the village clinic could be co-located.

11.1.3 Potential Benefits

The health care eBay may deliver a number of po-tential benefits. Some of these benefits are shared byany remote diagnosis systems, while the other bene-fits are unique or more pronounced in our proposedsystem.

One of the most important functions of the sys-tem is to allow competent medical professionals tocontribute at a time and from a location of theirchoosing. Good doctors take much time and resource

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to train and their services are always in great de-mand everywhere. Given options of where to prac-tice, many doctors are reluctant to serve in rural areasor in the developing world. India, for example, expe-riences a serious “doctor drain” today: a large num-ber of competent doctors practice in western coun-tries, where they earn much more than at home.

Having made the move, however, many still feelambivalent about their choices; and if given an alter-native which allows them to serve those left behind insome capacity, many would be eager to embrace theopportunity. Similarly, many doctors who live in ur-ban areas would be willing to serve a rural clientele ifflexible arrangements can be made. While any remotediagnosis system may help and there are other venuesfor people to volunteer their services, the health careeBay, as a central clearinghouse, may be particularlyeffective at harvesting and channeling this pool ofvolunteerism. One may, for example, easily chooseto answer just a few medical email questions abouta particular medical issue from a chosen region perweek—such “fine-grained” small contributions couldhave easily been lost without this system, but whensuccessfully harvested, these small efforts from manymay add up to a large overall impact.

A browse and search interface of the clearinghouseallows doctors to efficiently and flexibly choose whatcases they desire to examine. They may group sim-ilar cases together so they can all be dealt with ina similar fashion. They may prioritize based on ur-gency, so the more urgent cases are less likely to belost in the “clutter” of a system. They may choosespecific regions or communities that have the great-est needs to serve first. All these factors may allowdoctors and potential patients to be more efficientlyconnected with each other, and allow doctors to bet-ter utilize their time. (While maximizing efficiencyis important, the system does not rule out more per-sonal connections so, for example, it is possible fora doctor and a remote patient to maintain a longer-term connection.)

In traditional settings, where the nearest hospitalmay be many miles away, transportation is difficultor costly, and a patient is often made to stand in longqueues for hours, the patient becomes more reluctantto seek early diagnosis or treatment. Valuable timecan be lost, and by the time the symptoms worsento the point that the patient is forced to seek care,interventions can be too late, too expensive, or toodifficult to make a difference. A benefit of any remotediagnosis system is that by making the health care

information and services more easily accessible, pa-tients in remote regions are likely to seek care earlierand more often in the early stages of the symptoms.Such early interventions have been shown to signifi-cantly reduce the cost of the health care system.

The case of early intervention can be especiallystrong for the system that we propose. Because of thepervasiveness and the low cost of the Postmanet com-munication mechanisms, the infrastructural needs ofour proposed health care eBay system are minimal.The low cost and ease of deployment of such a systemthus can make it more widely available than other re-mote diagnosis systems. A greater number of villagesmay be reached; the overhead for patients to seek careat these village clinics can be even lower; so patientsmay be even more likely to seek early care.

11.2 Voice Mail

The poor spends disproportionally more (in terms oftime, labor, and money) on communication [14]. Pre-vious ICT experiences in the developing countries [3]suggest that variations of voice or email communi-cation are among the most useful and most popular“killer apps.” Success stories include the well knownGrameen “phone ladies” in Bangladesh (who loanedcell phones to fellow villagers for a fee), the Brazil-ian “virtual telephones” (which provided voice mailboxes to those who have no regular telephone ser-vice), and a South African experiment that providedemail service to residents at post offices.

In this subsection, we discuss a voice mail applica-tion built on top of all three key infrastructural com-ponents: the Postmanet, EdTV, and the repositoryabstraction. Although it is not necessary to have allthese components, a voice mail system built on top ofall three can offer some unique advantages: the Post-manet can offer large bandwidth and universal accessat a low cost, EdTV plays the role of demand aggre-gation and makes the service available to anyone infront of a conventional TV, and leveraging the repos-itory abstraction makes the application easy to build.The voice mail application is not only useful as a stan-dalone service, but also as a part of other higher-levelservices, such as the distance learning and health careapplications that we have discussed in previous sec-tions.

The voice mail application uses the EdTV setupshown in Figure 4. An end user in front of a regu-lar TV screen “activates” the voice mail applicationusing an inexpensive input device (which is either a

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walkie talkie or a custom-made ham radio transmit-ter). The voice mail application runs on the villagecomputer, which receives the end user input via aradio receiver directly attached to it. Once the appli-cation is instructed to enter the “record” mode by theend user, it can simply capture the user voice inputverbatim. To simplify input tasks such as specifyingdestination addresses, we can ask users to “hardwire”a number of possible recipient addresses ahead of time(as they “sign up” for the service, for example, po-tentially in front of the village computer, with the aidof a staff). While the availability of a TV screen isnot strictly necessary for this setup to work, it cansignificantly simplify the user interface.

The captured voice mail may leave the village com-puter via the Postmanet on a DVD. This arrange-ment allows a user to speak as much as she desiresvirtually for free! At a place where other types ofconnectivity alternatives are non-existent, the Post-manet is the only option. At a place where a low-latency low-bandwidth alternative, such as a cellularlink or a packet radio link, exists, a user of the voicemail system may choose between this more expensive,lower-bandwidth, but instantaneous alternative andthe cheaper, larger-capacity, but slower Postmanet.The incoming voice mails are delivered over the TVsignal sent by the transmitter attached to the villagecomputer.

Some general issues of EdTV that we have dis-cussed in Section 7.3 obviously apply to the voicemail application: one may get a “busy signal” if an-other person in the same village is already using thesystem; and there is no privacy as everyone withinthe transmission range can hear or see the radio andTV signals—if privacy is a concern, one has to walkto the village computer and use the voice mail appli-cation there. As we have discussed, we may pick andchoose which of the three infrastructural componentswe desire to use: we may bypass the EdTV compo-nent and gain some privacy at the expense of losingsome convenience, or we may bypass the Postmanetcomponent and gain some latency advantage (if a cel-lular or packet radio link is available) at the expenseof limited capacity and higher cost. And the loss ofprivacy over EdTV can also be turned into an advan-tage: for example, voice mails broadcast or collectedover the air wave allow group communication oppor-tunities that one may not usually have easy accessto.

11.3 Shopping on EdTV

In this subsection, we discuss a hypothetical shop-ping application. The purpose of this discussion isnot necessarily about this particular application sce-nario per se—instead, we use this application as arepresentative of a class of multi-user services thatcan be delivered over EdTV.

11.3.1 How Does It Work?

We again assume the EdTV setup of Figure 4. Un-like in the voice mail application discussed above, wenow assume the presence of a human operator man-ning the village computer when the shopping serviceruns. At an hour pre-agreed upon, villagers tune theirTVs to a shopping channel, whose signal is fed by thetransmitter attached to the village computer. Thevillage computer operator browses a shopping website at a leisurely pace. Whatever the operator seeson the village computer screen is transmitted to allthe TV screens in the village.

If the village computer has a conventional Internetconnection, the content of the shopping web site maybe retrieved from a remote web server in real time. Ifthe village does not have a conventional network linkto the outside world, the content of the shopping website could have been delivered to the village computerearlier via the Postmanet. (See Section 5.)

As the villagers watch the shopping site on theirTV screens, they simply jot down their desired trans-actions using pencils and paper. (Note that the“shopping site” here can also be an auction site.) Us-ing walkie talkies, the villagers may send the operatorsome simple requests such as pausing on a page or go-ing back to a previous page. If there are conflictingdemands, the human operator plays the role of anarbitrator (like a DJ).

Note that the operator essentially becomes an inte-gral part of a multi-user interface for a shared shop-ping application in this scenario. An existing tradi-tional shopping site may not even need to be mod-ified. Although it is theoretically possible to builda more automated user interface that eliminates theneed of the human operator and to allow villagers todirectly control the village computer using their inex-pensive input devices (discussed in Section 7.4), thisdegree of automation may not be necessary and thehuman operator solution has its advantages that maybe difficult to replicate.

The next day, the villagers walk to the “village TVstation” and hand their pieces of paper, which contain

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their desired transactions, to the village computer op-erator, who enters the villagers’ desired transactionsinto the computer. These electronic requests wouldleave the village computer via a conventional networkconnection, if one is available, or otherwise, a Post-manet connection.

Depending on the nature of the transactions (suchas whether it is an auction), the outcomes of thebuy and sell “orders” placed by the villagers in ear-lier days may be electronically delivered to the vil-lage computer via some sort of network, and furtherEdTV viewing sessions, which can be either personalor shared, may be scheduled by the operator to de-liver the “news” to his fellow villagers.

Note that all we have accomplished at this pointis “information hookup”—the exchanges of physi-cal goods yet need to take place. The informationhookup, by itself, however, is valuable. For exam-ple, in a traditional setting, a villager may producesome goods on a hunch, walk many miles to a bazaar,and wait hours for a potential buyer to stumble uponhis goods, if he is lucky. With an information hookup, the producer may expect to reach a wider au-dience, and only does the walking (or even the pro-duction) when he knows that a pre-arranged buyer iswaiting for the goods being sold. This is a more effi-cient process. More efficient physical exchanges mayalso be possible when the information hookup per-mits better demand and supply aggregation, so forexample, an enterprising third party could drive anauto-rickshaw to the bazaar on behalf of the wholevillage on a weekly or daily basis to handle the phys-ical exchanges pre-agreed upon electronically.

11.3.2 Potential Advantages

One may wonder what this shopping application pro-vides that a shopping channel on nation- or state-runTV cannot do. The differences are big. First, aswe have discussed in Section 7.2, EdTV is not TV: aregular TV is a mass media device, while an EdTVis a more personal media device that permits a highdegree of customization. In the shopping example,the goods that are being transacted and the times atwhich the shopping channel is played can be highlycustomized for the regions covered by small EdTVtransmission ranges. Second, the EdTV shoppingservice can be “powered by” a site that dynamicallypools requests from anyone who has any type of con-nectivity. This is a level of interactivity that regularTVs do not typically provide. Third, the shopping

mechanism discussed above requires almost no infras-tructural support: the villagers do not need access toa single phone, and the village computer powering thetransmitter does not even necessarily need a conven-tional network connection. Yet, the combination ofthe Postmanet and EdTV allows us to build a fairlysophisticated shared application, combining interest-ing features of existing Internet shopping and auctionsites with that of existing TV shopping channels.

The service described here also has potential ad-vantages over a shopping application delivered viaa traditional kiosk. First, an important function ofEdTV is to place interesting Internet applications onTV screens inside people’s homes, where end usersmay feel more comfortable spending a larger amountof time passively viewing it, leaving the “driving” tothe village operator, and not having to worry abouttying up a public device for long. A kiosk in a pub-lic location is a less comfortable way of “watchingTV,” which may explain why, while there are pub-lic phones, “public TVs” are not exactly popular.Second, unlike a conventional kiosk, which may in-cur a high cost on its network connection, the villagecomputer in the proposed system, can get a high-bandwidth feed via Postmanet virtually for free. Thelow cost and an improved experience (due to the highbandwidth) may attract more usage. The fact thatmost aspects of a shopping application are intrinsi-cally asynchronous makes it ideally suited for a high-latency network like the Postmanet.

Having speculated about the potential advantagesof such a hypothetical application, however, we rec-ognize that realistically building such a service mayinvolve many other complications, and we can be byno means sure that it would work. As we have said,the purpose of this discussion is not necessarily aboutthis application per se, and its details are not impor-tant. Our purpose is to use this example service toillustrate how a larger class of shared applicationsmay work on top of the infrastructural componentsdiscussed in this paper.

12 Conclusion

The Digital StudyHall system includes the followingkey components. (1) The repository is the center-piece. All the education content is collected in therepository, and all the digitally enabled human-to-human interactions are carried out through the site.For example, the lecture capture, homework feed-

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back, and question-answer session workflows are fun-neled through the repository abstraction. (2) ThePostmanet, and a particular application of it, thephttp mechanism, make the repository available tofringe villages. The Postmanet provides pervasive,high-bandwidth, and low-cost asynchronous connec-tivity to just about any place, including the remotestareas. (3) EdTV allows us to turn regular TV screensinto networked thin client displays. It lowers the costof end user devices, and it truly bridges the last mileby leveraging TV signals in one direction and radiocontrol signals in the other. EdTV opens up a “por-tal” for interesting computer-based applications intoa poor household that would have otherwise been be-yond the reach of more conventional technologies.

These components share a great deal of synergy.The phttp-accessible repository provides an abstrac-tion that is akin to that of a distributed file system,even to places that have no conventional connectiv-ity. The combination of the Postmanet and EdTVprovides a natural two-hop solution. And the repos-itory abstraction provides a convenient abstractionto build shared EdTV applications with. A commontheme of these components is that they allow shar-ing and the delivery of highly customized content andexperiences.

Using these components, we are building a Dig-ital StudyHall that allows resource-starved villageschools to benefit from the better human and con-tent resources available in the urban environments.We hope to connect learners and teachers across timeand space, and allow volunteers all over the world tocontribute toward the Millennium Development Goalof providing quality universal education!

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