Computer Physics Communications 127 (2000) 1–5www.elsevier.nl/locate/cpc

SimScience: Interactive educational modules basedon large simulations

Simeon Warner, Simon Catterall∗, Eric Gregory, Edward LipsonDepartment of Physics, Syracuse University, Syracuse, NY 13244, USA

Abstract

SimScience is a collaboration between Cornell University and Syracuse University. It comprises four interactive educationalmodules on crack propagation, crackling noise, fluid flow, and membranes. Computer simulations are at the forefront of currentresearch in all of these topics. Our aim is explain some elements of each subject and to show the relevance of computersimulations. The crack propagation module explores the mechanisms of dam failure. The crackling noise module uses everydaysounds to illustrate types of noise, and links this to noise created by jumps in magnetization processes. The fluid flow moduledescribes various properties of flows and explains phenomena such as a curve ball in baseball. The membranes moduleleverages everyday experience with membranes such as soap bubbles to help explain biological membranes and the relevanceof membranes to theories of gravity. We have used Java not only to produce small-scale versions of research simulations butalso to provide models illustrating simpler concepts underlying the main subject matter. Web technology allows us to deliverSimScience both over the Internet and on CD-ROM. To accommodate a target audience spanning K-12 and university generalscience students, we have created three levels for each module. Efforts are underway to assess theSimScience modules withthe help of teachers and students. 2000 Published by Elsevier Science B.V. All rights reserved.

PACS:01.50Ht

Keywords:Computer simulation; Education

1. Introduction

SimScience [1] is the work of four teams, each ofwhich has developed one module related to its researchwork. The modules are: Membranes, Fluid Flow,Cracking Dams and Crackling Noise. The moduleshave been developed to be essentially self-contained,yet are tied together with a common ‘look and feel’.

Our target audience spans K-12 and university gen-eral science students, a very wide range. To addressthis range of knowledge and ability we split each mod-ule into three levels, labeledadvanced, intermediate

∗ Corresponding author. E-mail: smc@physics.syr.edu.

andbeginning. The advanced level is for 11th gradeand higher (age 17+); the intermediate level is for 7th–10th grade (ages 13–16); and the beginning level isfor 6th grade and below (age 12−). The two higherlevels are well developed and have undergone evalua-tions which indicate that the level of material is aboutright. The beginning level is less well developed andtested.

In the rest of this paper we will pick out severalaspects of our approach to this work. We will focuson the membranes module because this is the one thatwe have developed.

This work builds on experience with the entry-levelgeneral-science course ‘Science for the 21st Century’

0010-4655/00/$ – see front matter 2000 Published by Elsevier Science B.V. All rights reserved.PII: S0010-4655(00)00028-X

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(offered by the Department of Physics at SyracuseUniversity [2]) and extends work described in [3].

2. Web technology, CD-ROMs and the Internet

The World Wide Web (WWW or simply ‘the Web’)is without doubt the most appropriate technology fordelivery of educational material of this type. Withthe addition of Java it is now possible to writesophisticated platform-independent programs that willload into the browser page.

In this work we use Java extensively. We also useJavaScript as necessary to overcome some incompati-bilities between different browser versions. Our mostnotable use is to resize the left-hand sidebar of ourlayout so that it correctly aligns with menu items andthe logo design. We have chosen not to use HTML(Hypertext Markup Language) frames because manybrowsers will not print then correctly and our expe-rience has shown that users can easily get lost whenusing browser ‘back’ buttons.

High-school teachers often do not have good In-ternet connections at home or at school, so we havefound it necessary to produce a CD-ROM version ofSimScience. Our philosophy has been to mimic theWeb version as closely as possible. Care is requiredto produce CD-ROMs that are usable in all the plat-forms we attempt to support, while preserving the useof long (longer than DOS 8+ 3 character) file names.This is achieved by including several sets of extensionsto the ISO-9660 CD-ROM standard: Joliet extensionsfor PC/Windows, HFS extensions for Macintosh, andRockRidge extensions for Unix. We have used thepublic domain programsmkhybrid andcdrecordto accomplish this.

The most fundamental difference between access-ing a set of pages on the Web and on a local file systemis that over the web there is a server program serv-ing, and perhaps processing, the pages whereas thisis not the case on the local filesystem. On the Web,server-side scripts are often used to implement searchengines and databases but this is not possible with aCD-ROM version. Thus to allow us to produce a CD-ROM version ofSimScience we have avoided the useof server-side scripts. This has particular impact on theimplementation of a search engine, which is discussedbelow.

3. Structure and design

Simple, easy to understand navigation is very im-portant. The chances of a user managing to navigate aweb site are increased if the structure is simple so wehave tried to keep our modules that way. From the toppage there are links to each of the four modules. Eachof the four modules then has three levels. In the mem-branes module we have a linear path through the mainsequence of material with branches to more discursiveessays. This is an attempt to reach a compromise be-tween a student-driven investigation and the desire forstudents to cover certain key points.

Within all modules clicking on the module titlelinks back to the top of the module, clicking onthe SimScience logo links to the mainSimSciencepage, and we use the same forward and backwardsicons throughout. These navigation ideas may soundtrivial but our experience has shown how importantconsistency is. At a recent evaluation, one module hadthe SimScience logo linking back to the top of themodule rather than the main page for the site. This waslisted under ‘dislikes’ by some of the students.

While we are careful not to create too many clut-tered and distracting links, some words are linked toglossary entries. When selected, a small glossary win-dow pops up with a definition. Subsequent selectionof glossary links in the main window or within theglossary definition just update the glossary window.We wanted to avoid the creation of a profusion of newwindows which can be very distracting or annoying,especially on low resolution displays.

In the membranes module we use a magnifyingglass icon to indicate links to essays ‘taking a closerlook’ at subjects described in the main text. Thereare also a set of menu items in the left sidebar (thesame for all pages), these link to: the introduction, themap, the search engine, the glossary and some helptext.

4. A search engine for Web and CD-ROM

The usual and sensible way to implement a searchengine on the Web is to have an HTML form to fillin for the search terms and method, the contents ofwhich are the inputs for a server-side script. This ishow popular search engines such as HotBot, AltaVista

S. Warner et al. / Computer Physics Communications 127 (2000) 1–5 3

and Lycos work. However, as we noted above, this isnot possible on a CD-ROM where there is no server torun the script.

Our approach has been to use Java to implementa client-side search engine. The immediate consider-ation here is the size of the database which must, atleast in part, be read by the client. For our modulesthe databases are a few 100 kB which is too large todownload in one file. Our approach has been to splitthe database into chunks based on the first letters ofthe index entries. This scheme still has a problem dueto the (sensible) restrictions of the Java applet securitymodel. Java applets may not access files on the localfile system, including the CD-ROM where the appletfiles reside, except to load class files. This means thatthe database chunks must be compiled into Java classfiles. The applet can then, at run-time, decide whichclasses (database chunks) need to be searched, andload them. Our search engine is currently configured touse database class files of between 4 and 8 kB whichgives acceptable performance both over the Internetand from CD-ROM. The database class files couldprobably be reduced to about half of their current sizeby using Javabyte arrays to store the data as opposedto JavaString s. This is because each character in aString uses two bytes to allow implementation ofunicode characters and make Java fully international.Our site is in English so there is no need for this gener-ality; restriction to ASCII characters would not createany problems.

We decided to limit the searches to individual mod-ules as we imagine students will work within one mod-ule at a time. The current search engine allows selec-tions of searches in one or all levels, for any or all of aset of words, and for exact matches or words that startwith the specified search terms. These controls havepurposefully been kept simple to avoid confusion.

We would like the search applet to return the resultsas a new HTML page, as most common search enginesdo. However, Java does not allow us access to thebrowser controls so we cannot dynamically create anew HTML page in the same way that a server-sidescript can.

5. Pictures, moving pictures and 3D models

Pictures are very important in material of the typewe are developing. Evaluations from students tend to

request more pictures. We can only go along so farwith this because many of the ideas we are tryingto communicate require text and we also hope tointroduce new vocabulary. The quality of images isalso important and we have had help from outside theproject team to render beautiful computer generatedimages.

If pictures are good, moving pictures are better.We use both animated GIF (Graphic Interchange For-mat, the GIF89a standard includes animation) imagesand movie clips in this work. However, movie clipsare somewhat problematic as the files quickly becomeprohibitively large, and they usually require an addi-tion ‘plug-in’ for the browser. Animated GIF imagesare very effective as they appear in the page, can bemade to run as a loop, and with care can have a rea-sonable file size.

To provide one further level of interactivity, wehave also written applets that allow a simple 3Dmodel to be rotated by the user. Such models couldbe implemented using VRML, but VRML has somedisadvantages: a ‘plug-in’ is required for browsers tosupport it, and VRML models cannot be embeddedin a HTML page so they are less well tied to theexplanatory text. One example we have is a model of ahuman red blood cell showing the distinctive discoticshape (Fig. 1). This has proved extremely popular inevaluations with all age groups.

6. Applets explaining concepts

We use many applets to help explain the conceptsunderlying our main subject matter. One is our ‘springapplet’ which is used to help illustrate the ideas offorce and energy for a spring under compression andextension. The applet allows the user to move one endof a spring while the other is fixed and plots out forceand stored energy graphs. Another is included withan essay called ‘Why are bubbles round?’ and is a2D analog of a bubble; there is a closed line with afixed area inside. The user can pull the perimeter intodifferent shapes or select certain pre-defined shapesusing buttons (circle, square, triangle, rectangle). Theapplet (Fig. 2) displays the length of the perimeter andthe goal is to allow the user to verify that they can notfind a shape with a smaller perimeter than a circle (forfixed enclosed area).

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Fig. 1. Screen image of applet showing 3D model of a human redblood cell. The model may be rotated by dragging with the mouse.The ‘coarser’ and ‘finer’ buttons change the definition of the grid toshow the model more or less smoothly.

It is extremely important that applets be as straight-forward and as intuitive to use as possible. We havefound that instructions are generally only consulted af-ter the ‘play phase’ where students just try to see whathappens – they have no fear of experimenting. Fromevaluations, we see that students are very easily dis-couraged if the can not get an applet to ‘work’ quickly.

7. Large scale simulations

Each of the groups responsible for theSimSciencemodules has a research interest employing large scalesimulations, and one of the aims of this project is tohelp explain the motivation behind these supercom-puter simulations. We have put most effort into ex-plaining why simulations of this type are importantand what they will help us to understand. The differ-ent teams have take different approaches to includeeither remote simulations, smaller scale Java simula-tions or canned movies from large simulations. As theproject has progressed we have de-emphasized this as-pect because we see that our research simulations aretoo complex and too time consuming (even on su-percomputers) to be of much use in a teaching con-

Fig. 2. Two screen images from applet which allows experimentalsearch for the shape with smallest perimeter for fixed enclosed area.Several predefined shapes can be selected with the buttons or anarbitrary shape be created by “dragging” points on the perimeter(marked with circles). The area is fixed at 1 unit.

text. Instead, we aim to provide a flavor of this workand devote most of our effort to explaining the back-ground.

S. Warner et al. / Computer Physics Communications 127 (2000) 1–5 5

8. Summary

We have outlined here some of the key pointsin the design and philosophy ofSimScience, wherepossible, in the context of the results of evaluations.Our experience has underlined the need for clarity inthe navigation and structure.

We have found Java to be and excellent vehiclefor interactive models and simulations. Java has alsoallowed us to implement a search engine that worksboth from CD-ROM and over the Internet.

Acknowledgements

In this paper we have described mainly the mem-branes module which is the work of the authors andMetin Sezgin, Shantenu Jha, Roberto Salgado, DavidRideout and Jackie Lagana. We have also mentionedelements from other modules which have been writ-ten by the following teams. Fluid Flow (Department ofMechanical, Aerospace and Manufacturing Engineer-ing, Syracuse University) – led by Hirsoshi Higuchiand including Michel van Rooij, Mustapha Guesmia,Toshiro Kiura, Jinzhong Zhang, Menko Wisee and

Samual J. Hund. Cracking Dams (Department of Engi-neering, Cornell University) – led by Anthony Ingraf-fea and including Ralph B. Robinson, Jeff Kerr, FrankNoschese, Magann Polaha, Nick Klein and Ari Be-lasen. Crackling Noise (Department of Physics, Cor-nell University) – led by James P. Sethna and includ-ing Mathew Kuntz and Paul Houle. Graphic design hasbeen done by members of the School of Visual andPerforming Arts at Syracuse University lead by Ed-ward Zajec and Bonnie Mitchell and included Yi HeYuhay Raymond Ng, Jon Celi and Toni Lee.

This work is supported by NSF grant ASC-9523481.

References

[1] SimScience URL: http://simscience.org/, also available on CD-ROM, email requests to request@simscience.org, commentsapreciated, send email to feedback@simscience.org.

[2] S. Catterall, M. Goldberg, E. Lipson, A. Middleton, G. Vidali,Implementation of information technologies in the teaching of‘Science for the 21st Century’, Intern. J. Modern Phys. C 8(1997) 49–66.

[3] S. Warner, S. Catterall, E. Lipson, Java simulations for physicseducation, Concurrency: Practice and Experience 9 (1997) 477–484.