The Effects of Using Touch-Screen Devices on Students’ MolecularVisualization and Representational Competence SkillsBrett M McCollum,* Lisa Regier, Jaque Leong, Sarah Simpson, and Shayne Sterner

Department of Chemistry, Mount Royal University, Calgary, Alberta T3E 6K6, Canada

*S Supporting Information

ABSTRACT: The impact of touch-screen technology on spatial cognitive skills asrelated to molecular geometries was assessed through 102 one-on-one interviewswith undergraduate students. Participants were provided with either printed 2D ball-and-stick images of molecules or manipulable projections of 3D molecular structureson an iPad. Following a brief introduction to common molecular shapes, participantswere assessed on their representational competence. In particular, learners weretested on their ability to match and construct molecular representations. Using thedevice for less than 15 min, iPad users exhibited increased ability to correctly identifyrelated chemical representations relative to learners taught with a paper-basedmethod. Even in the last stage of the experiment, without access to the iPad, asignificant difference between the two populations was sustained, with iPad-basedlearners demonstrating significantly higher representational competence thanlearners using the paper-based method. These findings suggest that touch-screen devices such as the iPad serve as effectivelearning technology for development of visuospatial and representational competence skills.

KEYWORDS: Chemical Education Research, First-Year Undergraduate/General, VSEPR Theory, Computer-Based Learning,Hands-On Learning/Manipulatives

FEATURE: Chemical Education Research

Interpreting two-dimensional representations of objects interms of their three-dimensional properties is a necessary

skill in chemistry,1−4 as well as other fields such as biology,geology, geography, agriculture, and fashion.5−11 In addition tomathematical reasoning and verbal abilities, spatial skills are oneof the major ability domains in the structure and organizationof human abilities.12,13

Molecular representations play a fundamental role inchemistry in that they permit a scientist to infer behaviorincluding state and reactivity.14,15 When reviewing the use ofvarious representation systems to convey chemical information,Habraken says (ref 15, pp 90−91):

Chemists cannot talk to each other without the use ofdrawings and, increasingly so, by using computer-generatedpictures and molecular models. Because, in chemistry, thepicture has become more than this; it has become a way ofthinking and the dominant way of thinking. ... The evolutionfrom the first primitive drawings of 125 years ago to today’scomputer-generated drawings is a clear demonstration of thesimultaneous evolution of a science and its scientific language.To the frustration of many chemistry neophytes, molecules

are too small for all but the most sophisticated instruments toimage.16 For this reason, chemists rely on modeling kits to trainstudents on the three-dimensional structure of molecules.17

While it was once said that “painted balls connected by rods areless like real atoms than department-store mannequins are likereal women”,18 these modeling kits continue to be an invaluableresource in chemistry. Modern modeling kits typically contain

plastic balls and connectors that permit particular fixed spatialarrangements that correspond with the geometries predicted byvalence shell electron pair repulsion (VSEPR) theory.19−22

There are arguments for expanding the chemistry educator’stoolkit beyond physical models.23,24 Multiple learning modesfor molecular modeling have been shown to improve studentperformance.25 It is now common practice to use both 2Dimages, such as those found in textbooks, and 3D physicalmodels when teaching VSEPR Theory. However, use ofmolecular representations require learners to develop somelevel of representational competence, a spectrum of skills forinterpreting, transforming, coordinating, and constructingexternal representations used when learning or problem solvingwithin a specific domain.26−29 For instance, mathematicsinstruction of children involving multiple external representa-tions draws heavily upon representational translation andcoordination skills, the ability to translate between differentrepresentations and coordinate complementary information notnecessarily found in both representations.30 In the field ofchemistry, experts and novices can be identified based on theirability to translate and coordinate multiple representations ofchemical phenomena.26 Harle and Towns provide an excellentreview of research on spatial ability and how it can informteaching and learning in chemistry.31 Chemical instructionmust involve both content delivery as well as representationalcompetence training.

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With current students living and growing up in atechnological age, many students have access to complexcomputer systems and games. Interactive computer softwarehas been used to improve student success with molecularvisualization.32,33 Furthermore, combined use of both physicalmodels and computer images leads to improvements instudents’ higher-order thinking skills.2

The iPad is a tablet computing device from Apple, Inc. thatpermits multiple simultaneous touches and gestures. Theadvent of touch-screen technologies, such as the iPad, providesa means to bring interactive computer images into theclassroom, and this can easily be combined with molecularmodels in engaging learning activities. Herein we determine ifthe iPad can be classified as teachnology, technology that whenused appropriately is an effective tool for teaching and learning.In this study, we focus on evaluating students’ matching (e.g.,

representational transformation) and construction (e.g.,representational construction) skills when using either 2Dprinted images of molecules or manipulable 2D projections of3D molecular images on an iPad. As would be expected in aclassroom environment where students are interacting withmultiple external representations from a variety of sources, thetransformation exercises generally also required mental rotationof the representations. No attempt was made to isolate thesetwo related tasks.

■ METHODOLOGY

Participant Qualifications

Participation in the study was restricted to undergraduatestudents who had not previously taken General Chemistry I, orits equivalent at another institution. At our institution, thepopulation in introductory chemistry is primarily sciencemajors, but also includes students from diverse programssuch as psychology, business, and aviation. To properly capturethe mixture of abilities and backgrounds observed inintroductory chemistry, participation was open to students inall faculties. However, a vast majority of volunteers werestudents in the first year of the BSc program and its feederupgrading courses. Although all BSc students will havecompleted high school chemistry, their knowledge of moleculargeometries is mostly limited to the shape of the water molecule.In total, 102 interviews were conducted with individual

participants by one of four undergraduate research assistants.Research assistants strictly followed an interview script tomaintain consistency. Participants were randomly assigned toone of two groups: paper-based or iPad-based learning. Thedistribution of participants according to gender (47 males, 55females) is shown in Table 1. To determine if a differenceexisted between the two populations in terms of their pre-existing visual-spatial ability a preassessment test using 16Shepard and Metzler type mental rotation test items wasemployed.34 However, on the basis of funding limitations andthe large number of participants (102 participants), it was notpossible to provide this preassessment to all participants.

Instead, to reduce the length of the majority of interviews, asample of 5 participants from each group was randomlyselected and underwent the preassessment test prior to theremainder of the interview. Many statistical tests, such as theMann−Whitney U-test, can be applied to samples of this size.35

The means scores for the paper and iPad groups were 12.2 and11.8, respectively. Applying the two-tailed Mann−Whitney U-test to the results demonstrates that the two populations can beconsidered equivalent at a significant level of α = 0.05 (n1 = n2= 5, U = 10 > 2 = Ucritical). Throughout the remainder of theinterview, all participants completed the same exercises, theonly difference being the medium used to present themolecular images.Data Collection

Interviews involved the five phases shown in Figure 1. Parts Aand B of the interview were instructional, while Parts C−E were

evaluative. Each stage had a time limit of 5 min. The maximumtime a participant used the iPad was 15 min (Parts A, C, andD). Interviews were video recorded with the consent of theparticipant.Participants had not yet encountered VSEPR Theory in their

coursework at the time of their interview, and thus, the purposeof Parts A and B were to introduce the participant to themolecular representations that were used throughout theremainder of the study. To simulate the time restrictions of aclassroom learning experience, participants were limited to only20 s per representation. Parts C and D were designed to assessthe impact of the medium (paper or iPad) on participants’matching skills. The final stage of the interview, Part E, wasused to determine if the medium influenced participants’construction skills. Learner inference skills were not examinedin this study, but are the subject of future work.

Table 1. Distribution of Participants According to Genderand Provided Medium

LearningMedium

Male Participants, %(N = 47)

Female Participants, %(N = 55)

Paper 48 52iPad 44 56

Figure 1. Interview process.

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The print images used in Part A were “ball-and-stick”representations of molecular geometries. Printed image areshown in Figure 2 alongside photographs of the correspondingphysical models used in Part B. Participants were permitted tohandle the print/iPad images and the physical models. Toensure that participants were establishing matches in Part Cbased on shape and not color, all molecular images weredesigned to have white atoms bonded to a central gray atom.Due to the available components in the modeling kits, thephysical models used black balls for the central atom in all 2-,3-, 4-, and 5-coordinate geometries, while the 6-coordinateshapes used a central gray atom. The same representations werepresented to iPad participants using an iPad and the“Molecules” mobile app.36 This app renders ball-and-stickmolecular representations that can be manipulated in a 3Dvirtual space through the iPad’s touch-screen interface.Molecular structural data for the VSEPR shapes used in thisstudy are included in the Supporting Information. The primarydifference between participant experiences was that iPad userscould use the functionality of the iPad to manipulate theorientation of the image.In Part C, participants were presented with the same

molecular images as in Part A and asked to identify thecorresponding physical model from Part B. The order of theimages was different from Parts A and B, but consistentthroughout all interviews. For each proposed match, partic-ipants were told if their selection was correct or not beforemoving on to the next image. The purpose of informing theparticipant on the accuracy of each proposed match was toprovide a small amount of feedback similar to a classroomexperience.Before beginning Part D of the experiment, the iPad/paper-

based images used in Parts A−C were taken away from theparticipant, but the physical models were left within reach ofparticipants for reference. Participants were instructed on howto interpret structural formulas in terms of the 3D nature ofwedged and hatched bonds (see Figure 3). Structural formulas

are not part of the provincial secondary school curriculum, andit is not expected that participants will have had priorexperience with this type of representation. They were thengiven a sheet with a set of four numbered structural formulas.To avoid participants seeking nonverbal clues from theinterviewer, they were provided envelopes labeled 1, 2, 3, and4, corresponding to the four structural formula options. A single“ball-and-stick” molecular image (paper- or iPad-based) wasthen given to the participant, and they were instructed to openthe envelope for the structural formula that matched the imageand check if they were correct. When a match was proposed, anew set of materials was given to the participant for them torepeat the process with another molecule. If a second matchwas proposed before the time limit of 5 min was reached, then athird set of materials was presented. Each set of molecularimages and structural formulas options used in the experimentis shown in Figure 3. Note that some of the colors for atoms donot match the standard colors used by chemists. This is aconsequence of the limited options in the Molecules app.Before Part E, the iPad/paper-based images used in Part D

were taken away from the participant, but the physical modelswere left within reach of participants for reference. For Part E, asingle structural formula, shown in Figure 4, and a modeling kitwere provided to participants. Participants were instructed toconstruct a physical model of the molecule with the correct 3Dspatial arrangement of atoms.The scoring system implemented for each stage of the

experiment was related to the design of the correspondingexercise. In Part C, students earned a score out of 11 pointsbased on the number of correct matches. For each of theexercises in Part D, it was recorded whether participantsidentified the correct structural formula. The scoring system forPart E measured how closely their model matched key featuresof the correct structure. These features are listed in Table 2.

Figure 2. “Ball-and-stick” molecular representations used in Parts A−C of the study along with photographs of the corresponding physical models.The VSEPR names for the structures shown are (a) Linear, (b) Trigonal Planar, (c) Bent or Angular, (d) Tetrahedral, (e) Trigonal Pyramidal, (f)Trigonal Bipyramidal, (g) See-saw, (h) T-shaped, (i) Octahedral, (j) Square Pyramidal, (k) Square Planar.

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■ RESULTSParticipant performance during Part C is reported in Table 3. Abox-plot of the data is provided in Figure 5. The discrete-valueddata sets follow exponential distributions and the appropriatestatistical tool is Welch’s U-test.37,38 The significance levelselected for this study was α = 0.05.In the case of Part D, the data is binary, and therefore,

Fisher’s Exact Test is appropriate.39,40 Results are listed inTables 4 and 5.Similar to Part C, data from Part E of the experiment are

integer valued scores and thus were analyzed using Welch’s U-test. The results are given in Table 6 with a corresponding box-plot shown in Figure 6.

Figure 3. “Ball-and-stick” molecular images and structural formulasoptions used in Part D of the study. (a) Option 2 is correct. (b)Option 4 is correct. (c) Option 3 is correct. The options for moleculeD-1 are cis-/trans-isomers, while the options for molecules D-2 and D-3 are stereoisomers. These topics are taught in organic and inorganicchemistry. This assessed how well learners could synthetically discoverthese types of spatial relationships without formal instruction.

Figure 4. (a) The structural formulas used in Part E of the study; (b−e) examples of participant responses. The correct answer is image b.

Table 2. Scoring System for Part E

Item Key FeatureCorrect

Characteristica

1 Geometry at the carbon atom Tetrahedral2 Geometry at the phosphorus atom Trigonal

bipyramidal3 Geometry at the nitrogen atom Trigonal

pyramidal4 Number of hydrogen atoms attached to the carbon 35 Number of hydrogen atoms attached to the

phosphorus2

6 Number of chlorine atoms attached to thephosphorus

1

7 Number of hydrogen atoms attached to thenitrogen

2

8 C−P−N bond angle 180°9 All atom colors match those listed below the

structural formula10 Nothing extraneous on the model

aOne point was earned for each of the listed features that matched thecorrect model.

Table 3. Participant Performance on Part C

ScoreaPaper-Based Participants

(N = 48)iPad-Based Participants

(N = 54)

11 15 4510 13 89 8 18 3 07 6 06 2 05 0 04 1 03 0 02 0 01 0 00 0 0

aThe Part C task involves matching physical models to provided “ball-and-stick” molecular images.

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■ DISCUSSION

Matching Molecular Representations

The results for Part C clearly demonstrate that students withaccess to the iPad outperformed their paper-based peers on thefirst assessment exercise. Although higher spatial ability onmental rotation tasks has been identified in males,41 the twopopulations had approximately the same gender distributionswith a slighting higher female percentage in the iPad group.Thus, it is not expected that gender is responsible for theobserved performance difference. The variance of performancewas substantially lower for iPad users. This may suggest that thetouch-screen is narrowing the performance gap betweenstudents. Alternatively, because most iPad users scored aperfect 11 on this stage of the experiment, this test was nolonger able to differentiate between strong and weak learnersamong the iPad group. It is likely that the results are impactedby both factors.The difference in performance by the two populations (paper

and iPad users) on both molecules D-1 and D-2 is significant.The difficulty of the tasks in this stage increased from locating aplane of symmetry to identifying centers of chirality.Approximately 20% of participants ran out of time beforereaching D-3. Additionally, most participants who started thethird structure did not have enough time and commented thatthey were guessing. Consequently, there is no significantdifference between the two groups in the D-3 exercise, and theresults for both groups correspond with random guessingwithin statistical errors.It was observed that iPad users took longer than paper-based

learners on exercises C and D. While many participants usingthe iPad would randomly change the molecular orientation,perhaps to internalize the structure, a few discovered that theycould adjust the image so that the bonds would match those ofthe structural formula and thus begin canceling out optionswhere one or more groups could not be positioned correctlyregardless of orientation. These purposeful participantsperformed better. The benefits of tactile interaction inchemistry has also been reported by Stieff.42 He observedthat external actions on physical models improved studentrepresentational translation skills in organic chemistry whensupported by expert instruction.Constructing Molecular Representations

Examples of participant responses to Part E are shown in Figure4. One of the most common mistakes in the paper-based groupwas a lack of recognition of the different types of positions(axial versus equatorial) surrounding the phosphorus atom and

Figure 5. Box-plot of participant performance in Part C as a functionof technology (n[paper] = 48 and n[iPad] = 54). Many participantswho used the iPad earned a perfect score of 11. *P = 4.6 × 10−7 ≪0.001.

Table 4. Participant Performance on the Three Exercises inPart D

Participants’ Results, Nb

Exercisea Medium Correct Not Correct

D-1 Paper 26 22iPad 42 12

D-2 Paper 6 42iPad 23 31

D-3 Paper 8 31iPad 6 37

aThe Part D task involves identifying a structural formula that matchesa provided “ball-and-stick” molecular image. bThe number ofparticipants for Part D-3 is lower than the the number of participantsfor previous parts because many participants ran out of time beforegetting to this stage.

Table 5. Performance Statistics for Part D

Exercise Npaper, NiPad Two-Tailed p-Value,a

D-1 48, 54 0.02D-2 48, 54 0.0009D-3 38,b 43b 0.56

aA significant difference (α = 0.05) emerges between participants’performance on exercises D-1 and D-2, but not D-3. This is likely theconsequence of participants running out of time to complete the thirdexercise. bThe number of participants for Part D-3 is lower than theprevious parts because many participants ran out of time before gettingto this stage.

Table 6. Participant Performance on Part E

ScoreaPaper-Based Participants

(N = 48)iPad-Based Participants

(N = 54)

10 11 229 15 188 5 37 6 56 4 35 4 34 2 03 0 02 0 01 1 00 0 0

aThe Part E task involves constructing a physical model from aprovided structural formula.

Figure 6. Box-plot of participant performance in Part E as a functionof technology (n[paper] = 48 and n[iPad] = 54). Those who had usedthe iPad in the earlier stages of the experiment generally were better atconstructing a physical model. *P = 0.018 < 0.05.

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thus the linear relationship of the C−P−N moiety. Aligningwith the other assessments, the mean scores for the twopopulations in Part E were found to be statistically different.Participants who used the iPad in earlier stages of theexperiment did better at this construction exercise, eventhough they did not have access to the iPad during thisassessment. On the basis of these results, the iPad, as amanipulable touch-screen technology, played an important rolein bridging students’ visuospatial understanding betweenstructural formulas and 3D physical models. The difference inperformance cannot be explained by offloading of cognitiveprocesses as the iPad was not used during the constructionphase. While each of the stages of this study could have beenconducted using a computer screen and mouse, it is unclear ifthe indirect manipulation would have yielded the same resultsas the tactile experience of the touch-screen tablet.

Learner Approaches to Problem Solving

The experience of paper-based learners was very different fromthat of the iPad participants. Generally, the paper group did notpick up the image but rather left it resting on the table. Veryfew participants rotated an image or angled it relative to theireyes. In agreement with Smith’s observations on embodiedcognition that cognitive development occurs when a learnerinteracts with their environment through sensory-motoractivity,43 paper-based users found the exercises increasinglychallenging and did not appear to develop coping techniques.As a result, the difference between the average performance ofthe two groups increased from exercise D-1 to D-2. This resultis also consistent with previous research that the requisiterepresentational competence and visuospatial skills for successin university chemistry must be developed through practice.2

The choice of initial orientation for the D-2 molecule may alsohave proven particularly challenging for the paper-basedlearners.It is important to consider that an alternative to participant

familiarity with the touch-screen interface of the iPad is thatlearners might be off-loading cognitive processes onto thedevice. However, that should not be as much a concern as onemight think. This off-loading process could be compared to theway scientists off-load menial computation to calculators,freeing them up to engage in more complex problem solving.Hambrick found that for geology novices, spatial ability was agood predictor of skill, mostly because the tasks expected ofthem required spatial ability and they had few copingtechniques.44 In contrast, spatial ability was no longer a goodpredictor of skill in experts. Hambrick refers to thisphenomenon as the “circumvention-of-limits”.45 Similarly, Stiefffound that when working with representations of 3-dimensionalmolecules experts employed very different mental processesthan novices, such as first identifying if planes of symmetry arepresent and only if none exist do they then attempt mentalrotation.46 In this way, experts employ additional copingtechniques and are less hindered by weak spatial ability thannovices. Uttal argues that spatial abilities matter in STEMeducation simply because they are a barrier that novices mustsurmount before participating in more advanced topics.47 Heproposes investments in spatial training on the basis that itcould yield significant dividends in student success. Thisresearch suggests that widespread implementation of tablettechnology in STEM education could help students surmountor even bypass the visualization barrier in introductory courses,increasing enrollment in upper-division and graduate chemistry

courses. Presumably, learners would adopt the mental processespracticed by experts that permit avoidance of complex time-consuming visuospatial manipulations. This agrees with theobservation that some groups of students demonstratepreference for algorithmic techniques over visuospatialmanipulations when conducting chemical problem-solving.3

Another benefit of student use of tablets when studyingmolecular geometries is the time savings relative to havingstudents construct physical models in lecture. Digitalrepresentations can be prepared by the instructor beforelecture affording the time to explore a greater range ofmolecular structures in class, and delivery to each student’stablet (via the course management site for instance) permitslearner-centric interactions with the representation as com-pared to an instructor demonstration.Review of the video recordings revealed that iPad users

performed an average of 30 hand gestures indicating mentalrotation as compared to an average of only 1 rotation gesturefor the paper-based learners. The disparity between groups isparticularly significant in light of Goldin-Meadow’s findings thathand gestures can indicate and promote learning.48,49 Gesturehad been shown to lighten cognitive loads and enhancelearning mental rotation tasks.50−52 The improved constructionability of iPad users, even without access to the iPad, suggeststhat use of the tablet has enabled some foundationalunderstanding or heightened spatial understanding of themolecular structure and connectivity not acquired by theaverage paper-based learner. This can be interpreted in thecontext of each representation’s design and functionality. Paper-based images are designed to be viewed; touching the pagedoes not cause the image to change. On the other hand, theiPad is a multitouch device that responds to user interaction.Participants would frequently alternate between touching theiPad screen and gesturing. Our interpretation of thisobservation is that the incorporation of a touch-screen deviceinto the educational experience promotes gesture, which in turnsupports visualization and learning.

Implications for Teaching and Learning

In addition to demonstrating the impact of touch-screentechnology on chemical education, this paper makes a strongcase for the reformation of traditional educational materials,namely, the printed textbook. Simply digitizing existing content,as is the case for most current eBooks, is not sufficient. Static“ball-and-stick” molecular images should be replaced withmanipulable molecular renderings. Without the real estaterestrictions and printing costs per page, it should be possible forauthors to provide complimentary representations to supportdevelopment of representational transforming and coordinatingskills.It should be kept in mind that our data supports the

replacement of static paper-based images with manipulabledigital ones. The data does not suggest any change in the use ofmolecular modeling kits. It is our opinion that manipulablemolecular images in a three-dimensional virtual environmenton touch-screen tablets serve to bridge student representationalcompetence between two-dimensional structural formulas andthree-dimensional physical models. All three modes ofrepresentation remain important in chemical instruction.Finally, success in university-level chemistry depends on a

student’s ability to visualize a molecule, describe the spatialrelationship of the atoms in various orientations, and predicthow portions of that molecule will interact with its

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surroundings. All of these skills relate to learners’ spatialabilities, visualization strategies, and molecular representationalcompetence, not their native language. This is promising in thecontext of the North American academic setting, where the firstlanguages of student populations are becoming more diverse.Use of a touch-screen to manipulate “ball-and-stick”representations of molecules, similar to molecular modelingkits, is not restricted by language barriers. In the field ofchemistry, where symbolic molecular representations are alanguage of their own, this is an advantage of touch-screenvisual aids over written educational materials.

■ CONCLUSIONS

Touch-screen technology was found to positively influencedevelopment of students’ visual cognitive skills. With minimalinstruction and less than 15 min use of the iPad, learnersdemonstrated enhanced matching skills relative to their peersusing paper-based images as measured by their ability to matchphysical models to molecular images and match structuralformulas to molecular images. Similarly, stronger constructionskills were observed among those who used the iPad duringearlier exercises based on their capacity to translate a structuralformula into a physical model of their own creation, eventhough the iPad was not used during the construction exercise.Touch-screen tablets improve upon the functionality of desktopand laptop computers with their increased mobility and relativeinexpensive nature; they make it possible to bring student-manipulable computer images into the classroom. Thus, inaccordance with Habraken’s view of an evolutionary chemicallanguage,15 touch-screen devices will likely play an importantrole in how chemists learn and communicate in the future.

■ ASSOCIATED CONTENT

*S Supporting Information

Molecular structural data for the 11 generic VSEPR shapes.This material is available via the Internet at http://pubs.acs.org.

■ AUTHOR INFORMATION

Corresponding Author

*E-mail: bmccollum@mtroyal.ca.

Notes

The authors declare no competing financial interest.

■ ACKNOWLEDGMENTS

This research was approved by the Mount Royal UniversityHuman Research Ethics Board. Financial support was providedby MRU. The iPad2 hardware is created by Apple, Inc. TheiPad application “Molecules” from Sunset Lake Software is freeto download from the iTunes app store.

■ REFERENCES(1) Copolo, C.; Hounshell, P. B. Using Three-Dimensional Modelsto Teach Molecular Structures in High School Chemistry. J. Sci. Educ.Technol. 1995, 4, 295−305.(2) Kaberman, Z.; Dori, Y. J. Question Posing, Inquiry and ModelingSkills of Chemistry Students in the Case-Based ComputerizedLaboratory Environment. Int. J. Sci. Math. Educ. 2009, 7, 597−625.(3) Stieff, M.; Ryu, M.; Dixon, B.; Hegarty, M. The Role of SpatialAbility and Strategy Preference for Spatial Problem Solving in OrganicChemistry. J. Chem. Educ. 2012, 89, 854−859.

(4) Stieff, M.; Hegarty, M.; Deslongchamps, G. IdentifyingRepresentational Competence with Multi-Representational Displays.Cogn. Instr. 2011, 29, 123−145.(5) Lazarowitz, R.; Naim, R. Learning the Cell Structures with Three-Dimensional Models: Students’ Achievement by Methods, Type ofSchool, and Questions’ Cognitive Level. J. Sci. Educ. Technol. 2013, 22,500−508.(6) Lennon, P. A. Improving Students’ Flexibility of Closure whilePresenting Biology Content. Am. Biol. Teach. 2000, 62, 177−180.(7) Kastens, K. A.; Agrawal, S.; Liben, L. S. How Students and FieldGeologists Reason in Integrating Spatial Observations from Outcropsto Visualize a 3-D Geological Structure. Int. J. Sci. Educ. 2009, 31,365−393.(8) Lloyd, R.; Hodgson, M. E.; Stokes, A. Visual Categorization withAerial Photographs. Ann. Assoc. Am. Geogr. 2002, 92, 241−266.(9) Nielsen, C. P.; Oberle, A.; Sugumaran, R. Implementing a HighSchool Level Geospatial Technologies and Spatial Thinking Course. J.Geogr. 2011, 110, 60−69.(10) Mitzman, S.; Snyder, L. U.; Schulze, D. G.; Owens, P. R.;Bracke, M. S. The Pilot Study of Integrating Spatial EducationalExperiences (Isee) in an Undergraduate Crop Production Course. J.Nat. Resour. Life Sci. Educ. 2011, 40, 91−101.(11) Park, J.; Kim, D.-E.; Sohn, M. 3D Simulation Technology Aas anEffective Instructional Tool for Enhancing Spatial Visualization Skillsin Apparel Design. Int. J. Technol. Des. Educ. 2011, 21, 505−517.(12) Carroll, J. B. Human Cognitive Abilities: A Survey of Factor-Analytic Studies; Cambridge University Press: New York, 1993.(13) Snow, R. E.; Lohman, D. F. In Implications of CognitivePsychology for Educational Measurement; Linn, R., Ed.; EducationalMeasurement; Collier MacMillian: New York, NY, 1989; pp 263−331.(14) Hoffmann, R.; Laszlo, P. Representation in Chemistry. Angew.Chem., Int. Ed. 1991, 30, 1−16.(15) Habraken, C. L. Integrating into Chemistry Teaching Today’sStudent’s Visuospatial Talents and Skills, and the Teaching of Today’sChemistry’s Graphical Language. J. Sci. Educ. Technol. 2004, 13, 89−94.(16) Gross, L.; Mohn, F.; Moll, N.; Liljeroth, P.; Meyer, G. TheChemical Structure of a Molecule Resolved by Atomic ForceMicroscopy. Science 2009, 325, 1110−1114.(17) Jones, L. L. Learning Chemistry through Design andConstruction. UniServe Sci. News 1999, 3−7.(18) Dement, J. J. Chem. Eng. News 1967, 45, 7.(19) Gillespie, R. J.; Nyholm, R. S. Inorganic Stereochemistry. Q. Rev.1957, 339−380.(20) Gillespie, R. J. The Valence-Shell Electron-Pair Repulsion(VSEPR) Theory of Directed Valency. J. Chem. Educ. 1963, 40, 295−301.(21) Gillespie, R. J. Electron-Pair Repulsions and Molecular Shape.Angew. Chem., Int. Ed. 1967, 6, 819−830.(22) Gillespie, R. J. The Electron-Pair Replusion Model forMolecular Geometry. J. Chem. Educ. 1970, 47, 18−23.(23) Gilbert, J. L.; De Jong, O.; Justi, R.; Treagust, D. F.; Van Driel, J.H. Research and Development for the Future of Chemical Education.Chemical Education: Towards Research-Based Practice; Kluwer Academ-ic Publishers: The Netherlands, 2002.(24) Jones, L. L.; Jordan, K. D.; Stillings, N. A. MolecularVisualization in Chemistry Education: The Role of MultidisciplinaryCollaboration. Chem. Educ. Res. Pract. 2005, 6, 136−149.(25) Geldenhuys, W. J.; Hayes, M.; Van der Schyf, C. J.; Allen, D. D.Receptor Surface Models in the Classroom: Introducing MolecularModeling to Students in a 3-D World. J. Chem. Educ. 2007, 84, 979−982.(26) Kozma, R.; Russell, J. Multimedia and Understanding: Expertand Novice Responses to Different Representations of ChemicalPhenomena. J. Res. Sci. Teach. 1997, 34, 949−968.(27) Kozma, R. B.; Chin, E.; Russell, J.; Marx, N. The Role ofRepresentations and Tools in the Chemistry Laboratory and TheirImplications for Chemistry Learning. J. Learn. Sci. 2000, 9, 105−144.

Journal of Chemical Education Article

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(28) Wu, H. K.; Krajcik, J. S.; Soloway, E. Promoting ConceptualUnderstanding of Chemical Representations: Students’ Use of aVisualization Tool in the Classroom. J. Res. Sci. Teach. 2001, 38, 821−842.(29) Nathan, M. J.; Stephens, A. C.; Masarik, D. K.; Alibali, M. W.;Koedinger, K. R. In Representational Fluency in Middle School: AClassroom Based Study; Mewborn, D., Szatajn, P., White, D., Wiegel,H., Bryant, R., Nooney, K., Eds.; Proceedings of the Twenty-fourthAnnual Meeting of the North American Chapter of the InternationalGroup for the Psychology of Mathematics Education ERIC Clearing-house for Science, Mathematics, and Environmental Education:Columbus, OH, 2002.(30) Ainsworth, S.; Bibby, P.; Wood, D. Examining the Effects ofDifferent Multiple Representational Systems in Learning PrimaryMathematics. J. Learn. Sci. 2002, 11, 25−61.(31) Harle, M.; Towns, M. A Review of Spatial Ability Literature, ItsConnection to Chemistry, And Implications for Instruction. J. Chem.Educ. 2011, 88 (3), 351−360.(32) Appling, J. R.; Peake, L. C. Instructional Technology andMolecular Visualization. J. Sci. Educ. Technol. 2004, 13, 361−365.(33) Stieff, M. Improving Representational Competence UsingMolecular Simulations Embedded in Inquiry Activities. J. Res. Sci.Teach. 2011, 48, 1137−1158.(34) Peters, M.; Battista, C. Applications of Mental Rotation Figuresof the Shepard and Metzler Type and Description of a MentalRotation Stimulus Library. Brain Cogn. 2008, 66 (3), 260−264.(35) Mann, H. B.; Whitney, D. R. On a Test of Whether One of TwoRandom Variables Is Stochastically Larger than the Other. Ann. Math.Stat. 1947, 18 (1), 50−60.(36) LarsonB.Sunset Lake Software Molecules, 2012.(37) Welch, B. L. The Generalization of “Student’s” Problem WhenSeveral Different Population Variances Are Involved. Biometrika 1947,34, 28−35.(38) Fagerland, M. W.; Sandvik, L. Performance of Five Two-SampleLocation Tests for Skewed Distributions with Unequal Variances.Contemp. Clin. Trials 2009, 30 (5), 490−496.(39) Fisher, R. A. On the Interpretation of χ2 from ContingencyTables, And the Calculation of P. J. R. Stat. Soc. 1922, 85, 87−94.(40) Agresti, A. A Survey of Exact Inference for Contingency Tables.Statist. Sci. 1992, 7, 131−153.(41) Geiser, C.; Lehmann, W.; Eid, M. A Note on Sex Differences inMental Rotation in Different Age Groups. Intelligence 2008, 36, 556−563.(42) Stull, A. T.; Hegarty, M.; Dixon, B.; Stieff, M. RepresentationalTranslation with Concrete Models in Organic Chemistry. Cogn. Instr.2012, 30, 404−434.(43) Smith, L. B. Cognition as a Dynamic System: Principles fromEmbodiment. Dev. Rev. 2005, 25, 278−298.(44) Hambrick, D. Z.; Libarkin, J. C.; Petcovic, H. L.; Baker, K. M.;Elkins, J.; Callahan, C. N.; Turner, S. P.; Rench, T. A.; LaDue, N. D. ATest of the Circumvention-of-Limits Hypothesis in Scientific ProblemSolving: The Case of Geological Bedrock Mapping. J. Exp. Psychol.Gen. 2012, 141, 397−403.(45) Hambrick, D.; Meinz, E. Limits on the Predictive Power ofDomain-Specific Knowledge and Experience for Complex Cognition.Curr. Dir. Psychol. Sci. 2011, 20, 275−279.(46) Stieff, M. Mental Rotation and Diagrammatic Reasoning inScience. Learn. Instr. 2007, 17, 219−234.(47) Uttal, D. H.; Cohen, C. A. In Spatial Thinking and STEMEducation: When, Why, and How?; Ross, B. H., Ed.; The Psychology ofLearning and Motivation; Academic Press: New York, 2012; Vol. 57,pp 147−181.(48) Goldin-Meadow, S. When Gesture Does and Does NotPromote Learning. Lang. Cogn. 2010, 2, 1−19.(49) Goldin-Meadow, S. How Gesture Promotes LearningThroughout Childhood. Child Dev. Perspect. 2009, 3, 106−111.(50) Goldin-Meadow, S.; Nusbaum, H.; Kelly, S. D.; Wagner, S.Explaining Math: Gesturing Lightens the Load. Psychol. Sci. 2001, 12,516−522.

(51) Goldin-Meadow, S.; Levine, S. C.; Zinchenko, E.; Yip, T. K.;Hemani, N.; Factor, L. Doing Gesture Promotes Learning a MentalTransformation Task Better than Seeing Gesture. Dev. Sci. 2012, 15,876−884.(52) Goksun, T.; Goldin-Meadow, S.; Newcombe, N.; Shipley, T.Individual Differences in Mental Rotation: What Does Gesture TellUs? Cogn. Process. 2013, 14, 153−162.

Journal of Chemical Education Article

dx.doi.org/10.1021/ed400674v | J. Chem. Educ. XXXX, XXX, XXX−XXXH