Using Variation Theory with Metacognitive ... - ACS Publications

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Using Variation Theory with Metacognitive Monitoring To Develop Insights into How Students Learn from Molecular Visualizations Resa M. Kelly* Department of Chemistry, San José State University, San José, California 95192, United States S Supporting Information *

ABSTRACT: Molecular visualizations have been widely endorsed by many chemical educators as an efficient way to convey the dynamic and atomic-level details of chemistry events. Research indicates that students who use molecular visualizations are able to incorporate most of the intended features of the animations into their explanations. However, studies also suggest that learning from visualizations is imperfect. In this study a new theoretical framework, variation theory, was used to examine learning and understanding based on students’ reported experience of variation while viewing visualizations. Student metacognition was examined to gain insight into how students recognized variation between their mental models and the visualization models. Results from this study provide visual evidence of a transitional state of understanding in which students’ previous conceptions merge with new conceptions learned from the visualizations. However, limitations in students’ ability to monitor their understanding made unpacking what students understood challenging, as students tend to communicate only what they believe to be the most essential details. KEYWORDS: High School/Introductory Chemistry, Chemical Education Research, Computer-Based Learning, Misconceptions/Discrepant Events, Qualitative Analysis FEATURE: Chemical Education Research

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INTRODUCTION Yeah, I’ve seen pictures, but, like, I don’t know. It doesn’t help me... picturing the atomic level doesn’t help my learning at all.

gained from viewing visualizations to revise their understanding. The goal of this study was to examine how students adapted their mental models of solid and aqueous sodium chloride tested for electrical conductivity to fit with features portrayed in molecular visualizations of the same events using picture construction and a metacognitive monitoring exercise.

− Student Li

Students find it challenging to understand and picture the particulate nature of matter.1−4 When students have limited atomic level understanding it becomes difficult for them to comprehend the behavior of particles and how that behavior is linked to macroscopic behavior. In the past, instructors focused on problem solving emphasizing the macroscopic and symbolic levels, which resulted in perpetuating the lack of connection to the submicroscopic levels.5−7 However, technological advances in the form of digital molecular visualizations have made it easier to picture the atomic level and make connections to the other levels. Many studies have examined the benefits of viewing visualizations to enhance students’ conceptual understanding of chemistry concepts.8−18 Often these studies report that students convey fewer misconceptions about the conceptual nature of chemistry after viewing visualizations of atomic level concepts, but some studies report that the impact of learning from visualizations is uneven and many students still retain imperfect understanding.19−24 Little research has been done to examine how students are processing information © XXXX American Chemical Society and Division of Chemical Education, Inc.

The Nature of Solid and Aqueous Sodium Chloride

Students convey a variety of alternative conceptions and/or misconceptions about aqueous salt solutions25−27 and the lattice arrangement of ions in solid sodium chloride.28−30 For example, many beginning chemistry students believe an aqueous sodium chloride solution to be composed of ion pairs or molecules.25−27 Some believe the molecules break apart into neutral atoms in solution, while others may think that solute forms bonds with water or reacts with it.25,26 In the case of solid sodium chloride, students also indicate that molecules are present within the ionic lattice structure with little understanding of the three-dimensional nature of the ionic solid.29−31 Kelly et al. reported that students may be reluctant to represent dissociated ions in representations of aqueous solutions and solid structures because of their focus on the symbolic formula representations.32 While most students

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dx.doi.org/10.1021/ed500182g | J. Chem. Educ. XXXX, XXX, XXX−XXX

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associate sodium chloride with ionic bonding, they often confuse terms and talk about “molecules of NaCl” held together by covalent bonds.29 Visualizations help many students to better understand that aqueous salt solutions are composed of hydrated ions in solution, but many students are unable to transfer this understanding to describe aqueous salt solutions involved in precipitation reactions.8,9 These are concepts that continually challenge our students.

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THEORETICAL FRAMEWORK

Variation Theory

The goal of this study was to learn what features students attended to when they monitored their understanding against the information presented to them in molecular visualizations and how their identification of differences and similarities inspired them to vary their oral and drawn explanations. As a result, a relatively new framework, variation theory, was used to guide the study. Variation theory is a theory of learning adapted from phenomenography that examines the critical features of a phenomenon, such as features portrayed in molecular visualizations, that learners attend to as they experience the phenomenon, and it calls into question why students experience these features differently?35 To discern aspects of a phenomenon, a student must experience and recognize the variation in that aspect.35 While learners may not recall all details of an experience, they do recall “critical features” that were important to them at the time they were experienced and that remain important to the learner over time. These features are likely the ones that anchor and continue to structure students’ understanding of the event.35 Thus, this methodology was used to examine learning and understanding based on students’ reported experience of variation while viewing visualizations. Two major constructs, mental models and metacognition, were examined in order to gain insight into how students recognized the presence of variation. A mental model is a personal representation, typically “visual-pictorial” in nature, of a concept that is used by learners to explain and make predictions about their surrounding world.36−38 Wang and Barrow suggest that mental model development is influenced by the learner’s efforts to incorporate content knowledge with visual-spatial thinking skills.39 Students must be able to visualize 3D molecular geometry shapes, understand principles that determine spatial arrangement, and have the ability to relate how these principles affect spatial arrangements.39 Thus, uncovering students’ mental models prior to and after viewing visualizations through picture construction and oral explanation was essential for understanding how students’ thinking and reasoning developed and varied after viewing visualizations.38 The second construct, metacognition, was examined to explore how students experienced variation as a result of viewing the visualizations. Metacognition is traditionally defined as the experiences and knowledge we have about our own cognitive processes.40 Essentially, metacognition is viewed to consist of two essential aspects: metacognitive knowledge and metacognitive skillfulness.41 Sandi et al. summarized these components stating that metacognitive knowledge refers to one’s explicit awareness of one’s cognition, whereas metacognitive skillfulness refers to how one regulates one’s cognition while performing a task.42 Activities in which the object of reflection is one’s personal knowledge or thinking are useful for developing one’s metacognitive skillfulness42 and when these activities are coupled to visualization-use, they require the student to articulate the critical features of the visualizations that inspired them to change, a goal of variation theory. The activity employed in this study was metacognitive monitoring because it explored how students’ experienced variation in their understanding of critical features portrayed in the visualizations. The act of monitoring required students to make judgments about their understanding while viewing the visualizations.

Understanding Electrical Conductivity

Since many students find it difficult to understand the particulate nature of both aqueous and solid sodium chloride, it is not difficult to reason that students would also find it challenging to understand how these substances respond when tested for electrical conductivity. Butts and Smith (1987) studied 12th year students’ understanding of how an electrolyte solution conducted an electric current and found that none of their participants could provide an accurate explanation of the events.29 It was typical for students to understand that charged particles were involved but students were confused by what the particles were.29 Specifically, students did not understand the role of ions in the process.29 In contrast, Tiechert et al. demonstrated that community college students who were presented with a conductivity context were more likely to draw and describe aqueous NaCl as made up of separated ions than they were in another context involving boiling point.33 Their study suggests that students strongly connect the macroscopic event of electrical conduction with their conception of the atomic level, but it is not clear whether students were able to go beyond recognizing that the ions were dissociated to account for how ion movement led to conduction or whether students believed that electrical conduction caused the ion pairs to separate.33 Examining Previous Studies and Exploring New Contributions

The transformation of students’ explanations of chemistry concepts before and after viewing animations has shown the positive impact visualizations have had on transforming students’ conceptual understanding of the particulate nature of matter.8,9,20−22 When students passively view molecular visualizations it is similar to learning from direct instruction. Essentially learners are processing the observed information and fitting it to their existing understanding.34 The knowledge people bring can interfere with their ability to learn what the visualization is trying to teach them. Kelly and Jones explored how the features of two different styles of molecular visualizations affected students’ oral, written and drawn explanations of sodium chloride dissolution.8 An important finding of this study was that while the majority of students made changes that improved upon their initial representations, many students had difficulty orally articulating why they changed their drawings or how the animation made sense to them. In addition, many students retained incorrect features in their drawn representations, but it was not understood why students retained these errors.8 In a similarly designed study, Rosenthal and Sanger explored how viewing two different animations affected students’ oral explanations of an oxidation− reduction reaction.20 They reported that sometimes students orally misinterpreted what they saw in animations and this could lead to misconceptions or errors in how students mentally picture chemistry events. B



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Table 1. Visualization Features of Solid Sodium Chloride Identified from Students’ Oral Descriptions as Similar to, Different from, or Both Similar to and Different from Their Mental Models of the Same Event Number of Students (n = 24)

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Visualization Features of NaCl(s)

Similar

Different

Similar and Different

Did Not Mention

Overall appearance−lattice, cube, 3-d, shape Proximity of atoms/ions Movement−atoms/ions vibrate No conductivity − ions stay in place, no movement to electrode Bond representation − ionic bonds, charge, presence of ions

10 3 4 5 3

6 3 6 5 5

6 6 1 7 4

2 12 13 7 12

RESEARCH QUESTIONS

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SETTING This study was conducted as part of a larger study completed outside of class time that examined how students’ explanations of substances tested for electrical conductivity evolved during two prior knowledge exercises and after viewing visualizations of the same chemistry events. The 24 students completed two exercises: (1) a worksheet requiring them to predict and justify whether a substance would conduct based on its chemical formula and (2) a Flash-based click and drag computer exercise where students constructed atomic level pictures to demonstrate their prior understanding of the electrolytic behavior of solid and aqueous sodium chloride. After these prior knowledge exercises, the students passively viewed 15 molecular visualizations of the same chemistry events, then students were prompted to metacognitively examine their understanding compared to the visualizations through question prompts by the interviewer (see Supporting Information for links to and descriptions of the molecular visualizations). Lastly, they were invited to make hand-drawn revisions to their initial click and drag pictures.

The central goal of this study was to investigate how students recognize variation between their mental models and the models featured in visualizations using a metacognitive monitoring activity and picture construction and revision. Specifically, in what ways do students recognize aspects of visualization features and adapt them to their mental models to create meaningful conceptions? This investigation was guided by the following research questions: 1 What kinds of visualization features do students identify as matching to or differing from their mental models and how do they express modification to their mental models in pictorial constructions and by using metacognitive monitoring? 2 How can the ways students use atomic level visualizations to construct understanding be categorized?

STUDENT PARTICIPANTS

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The students were drawn from a first-semester, general chemistry course for science majors at a western university in the United States and participated the last 4 weeks of the semester. The students volunteered to participate after an oral announcement was made during their class. Their instructor offered extra credit incentives for their participation in the study; however, he also provided an extra credit alternative for those unable to participate. There were 13 females and 11 males of diverse ethnicity with 17 students from Hispanic, Asian, or other minorities reflecting the general distribution of the University. All 24 students consented to participate; chemical element pseudonyms were used to protect their anonymity. During the study sessions, technical difficulties arose in collecting complete comparison data of aqueous sodium chloride for three students. Thus, for the study of the conductivity of aqueous sodium chloride, data for only 21 students were analyzed. The students who participated in the study had completed a laboratory on conductivity during the fourth and fifth weeks of the semester. The goal of the lab was to categorize substances as strong, weak or nonelectrolytes by measuring the conductivity with a hand-held, battery operated conductivity apparatus. The students also completed an electronic learning tool on precipitation reactions, where they viewed visualizations of two aqueous reactant solutions before, during, and after a reaction. Their course instructor did not lecture about conductivity; however, he had addressed the nature of solids, liquids, and aqueous solutions as well as ionic and covalent bonding and intermolecular forces of attraction by the time the students had participated in this study.

METHODOLOGY A semistructured interview and artifacts made by the students (click and drag atomic-level pictures and hand-drawn revisions to these pictures) were used to examine how students adjusted their mental models after viewing molecular visualizations. The semistructured interview was simplistic in its structure and the questions were presented with the specific intention of examining how students metacognitively monitored their understanding and adapted new information from the visualizations to fit with their understanding of the chemistry events. The interview began by asking students: 1. What did the visualizations teach you that was new or different from what you knew before? 2. What did the visualizations teach you that was similar to or matched what you knew before? As is typical of semistructured interviews, students were allowed to answer the questions and then the interviewer probed for deeper understanding by asking students to elaborate on their responses. At the end of the session, students were asked to self-assess their initial pictorial representations and they were instructed to make revisions to better reflect their new understanding. Following the study, the interviews were transcribed and an open coding process43,44 was applied to examine the students’ sense for how their understanding compared to the information presented in the visualizations. Axial coding44 was used to specifically identify how students’ explanations of similarities and differences compared to their pictorial representations and revisions, respectively. A constant comparative method of data analysis was employed to compare students’ self-identified C



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similarities and differences to the variations they illustrated in their drawn representations. Analysis of the data was extended to develop categories to describe how students used visualizations during the study. Validation of the codes was established through inter-rater reliability. A colleague examined the trustworthiness of the findings by reviewing the audit trail and confirmed the dependability of the coded data. In cases where disagreement occurred, which was a rarity (only 4 out of 450 codes), the data was reviewed and consensus was reached.44

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RESULTS AND DISCUSSION

Similarities and Differences Associated with Visualizations of Solid Sodium Chloride Tested for Electrical Conduction

Visualization Attributes. Structural appearance and conductivity were the most commonly referenced visualization attributes students identified when comparing their mental models to the visualizations (Table 1) indicating that these are features in which students most commonly sense variation. There was considerable range in how students described the appearance of solid salt as being similar and/or different to their mental models with some students acknowledging the lattice arrangement or the three-dimensional shape, while a few stated rather vaguely that it was “what the solid looked like” that matched or differed from their mental models. Intricate features, such as proximity of atoms/ions in the solid, vibrational movement of atoms in the lattice and the charge interaction between ions in the lattice went unmentioned by many students indicating that these were details that did not resonate as noticeable variations. Similarity or Difference. Several students recognized visualization features that matched their mental pictures, and also identified ways that the same features differed from their mental models indicating that they were able to assess how their understanding varied from the visualizations. However, there were also cases where students reported a similarity also as a difference, and it reflected that students were confused by what they viewed. For example, Student P initially represented solid sodium chloride as gaseous molecules randomly distributed. This is a perspective commonly reported in the literature (Figure 1A).29−31 When asked how her predictions compared to the visualization she shared, “I pictured it as a cube, but I didn’t know why.” When asked how her understanding differed from the visualization she stated, “They are close together to max the charges and its cube-like form.” She later revised her representation to look more like a cube, but she incorporated molecules or ionic pairs in the construction of the cube, revealing that she had difficulty letting go of her initial conception of molecules (Figure 1B). Imperfect Understanding. Consistent with previous studies, sometimes students demonstrated enriched understanding with drastically different pictorial revisions, but their oral reasoning implied that they might still hold imperfect understanding and might not fully understand the extent of variation between their mental models and the visualization models.8,9 For example, when Li was asked if anything in the visualizations matched her initial understanding, Li replied, “No, I don’t think so. Well, they’re ionic pairs, but nah, nah. I just did it wrong.” She admitted that she knew it was not conductive. When questioned about what aspects differed from her understanding, Li stated, “The ions are positioned in a three dimensional way and they’re not floating around like I

Figure 1. (A) Student P’s initial representation of NaCl(s) tested for electrical conductivity generated using a click and drag computer tool. (B) Student P’s hand-drawn revision of solid sodium chloride tested for electrical conductivity showing the persistence of molecular pairs as noticed by the vertical arrangement of pairs (two atoms that touch) within the cube.

represented it. They’re tied in together by ionic bonds.” Initially, Li constructed her representation of solid sodium chloride to have randomly spaced molecules of NaCl (Figure 2A), a look that is consistent with student misconceptions

Figure 2. (A) Student Li’s initial representations of solid sodium chloride tested for electrical conductivity generated using a click and drag computer tool. (B) Student Li’s hand-drawn revision of solid sodium chloride tested for electrical conductivity. D



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Table 2. Students’ Revised, but Flawed Representations of Solid Sodium Chloride Tested for Electrical Conductivity Compared to Their Oral Description of Differences Observed When Comparing Their Understanding to What Was Portrayed in the Visualizationsa

a

See Supporting Information for additional examples.

tions reported that the visualization matched “by how close they were” or how “sodium chloride was stuck together...” Evidence of a Transitional State of Understanding. Analysis of students’ orally articulated differences with revisions of pretreatment pictures they constructed after viewing the visualizations revealed that typically students (19 of 24) represented some or all of their orally articulated differences in their revisions. However, seven students who orally recognized differences changed their pictures in a manner that addressed the noted difference, but also conveyed flawed understanding (Table 2). The students may be reluctant to abandon explanatory principles that they had originally perceived as successful. Their revisions provide evidence of a transitional phase of understanding, in which students are between explanatory principles in their understanding.45 This is consistent with observations made by Taber to describe a student’s bonding explanations during a longitudinal study.45 He observed that as the student learned new information he was reluctant to abandon what was previously learned and experienced a transitional phase of understanding.45 In a few cases, students orally described a difference between the visualization and their understanding, but they chose not to change their pictures. For example, four students noticed that in the visualization, the ions of solid sodium chloride did not break apart, move toward the electrodes, or conduct electricity, yet none changed their pictures to reflect these differences, possibly indicating that they felt their previously constructed pictures were adequate for conveying the important aspects of the chemical event or that the variation did not merit change on their part. Only two students, F and Al, claimed that there were no differences between the visualization and their under-

previously documented in the literature.29−31 In her revision, she constructed a lattice with appropriate ion placement and it looked very similar to what was portrayed in the visualization (Figure 2B). She appeared to make noticeable improvement in her understanding based on her revision; however, she may also be very good at imitating what she saw in the visualizations. Thus, her oral description of the revision was useful in revealing the reason for her revisions. Li stated, “I drew the NaCl molecules in a 3d block, kind of three dimensional so that the Cl and the Na, Cl negative and Na positive ions would alternate.” Unfortunately, even with Li’s oral description it was challenging to know whether she misused the term molecules and meant to use the term ions or whether her use of the term molecule was a sign that she continued to think of sodium chloride as composed of molecules within the lattice. Student Says It Matches; Pictures Tell Another Story. Many students (11 of 24) initially constructed pictures that were visually dissimilar to the images portrayed in the visualizations, yet these students reported that their understanding matched the visualization (see Supporting Information to view students’ pretreatment click and drag pictures and oral descriptions). This is an indication that students may not fully understand how their mental models are at variance with what is observed in the visualizations. It is possible that the visualizations may have helped students recall forgotten concepts. For example, students Be and Ca, stated that they had seen pictures or visualizations like these before so it did not surprise them to see the cube representation. An additional complication may be that students have difficulty articulating their understanding, for example, four students (H, B, N, and Ar) who depicted ion pairs in their pretreatment representaE



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Table 3. Visualization Features of Aqueous Sodium Chloride Identified from Students’ Oral Descriptions as Similar to, Different from, or Both Similar to and Different from Their Mental Models of the Same Event Number of Students (n = 21) Visualization Features of NaCl(aq) Solute Completely dissociated into ions Solvent Hydration spheres Bulk water Description of solution movement (ions in water) Conductivity Electrode attracts oppositely charged ions

Similar

Different

Similar and Different

Did Not Mention

4

1

4

12

5 5 8

9 4 1

1 3 4

6 9 8

7

8

4

2

standing. In spite of this claim, both students made changes to their representations indicating that they detected variation and they were compelled to create improvements to better illustrate their understanding. Variations between Mental Models and Visualizations of the Conductivity of Aqueous Sodium Chloride

Visualization Attributes. The most commonly reported features that students reported as similar and different to their understanding of aqueous sodium chloride tested for electrical conduction were the general movement of solvent and solute species in solution and ion movement as a result of conduction (Table 3) indicating that these were features in which students sensed variation. Many students did not mention detailed structural characteristics such as the nature of solute or bulk water characteristics. This may be a result of the visualizations’ emphasis on the dynamic nature of the conductivity event distracting students from structural characteristics. One structural feature that received students’ attention was the presence of hydration spheres. A possible reason students may have been more attentive to this detail was that it was emphasized in pre-lab visualization exercises for precipitation reactions that students completed earlier in the semester; as a result, the visualizations may have triggered students’ recollection of this feature (see Supporting Information to examine examples of students’ pretreatment click and drag pictures and oral descriptions). Differences Addressed in Revisions. Consistent with the findings for solid sodium chloride, when students (17 of 21) orally identified differences after viewing the visualizations of aqueous sodium chloride tested for electrical conductivity, they usually addressed all or at least some of these differences in their hand-drawn revisions and demonstrated improved understanding. Many students (10 of 21) took shortcuts to depict their noted differences by only drawing a limited number of species to make their point. Unfortunately, some students (5 of 21) who addressed their articulated differences in their revisions also made changes that reflected the retention of flawed understanding. For example, four of the five students retained the misconception that ion pairs were present. In the case of student O, it was obvious that he never made the connection that the ions were separated. Student O stated, “Just how they were together but attracted to the opposite side still.” Interestingly, student P noticed that ion pairs broke down. In reporting the differences P stated, “They stay the same, but the charges line up with the poles. The Na breaks down with the Cl.” Student P revised her pictures to show ion pairs attracted to the electrodes (Figure 3). In describing her revisions, student P stated,

Figure 3. Student P’s drawn revision of aqueous sodium chloride tested for electrical conductivity demonstrates retention of ion pair misconception.

“I put the Cl’s facing towards the positive metal, the positive pole. I put this, the Na’s facing, they’re together, and facing the negative pole.” When reviewing student P’s transcription it was impossible to detect that she retained the misconception of ion pairs, but her revised picture clearly represented its presence. This finding was consistent with studies by Kelly and Jones who also reported that there could be a discrepancy between students’ oral explanations and drawings.8,9 When They Do not Revise. Several students (5 of 21) reported differences between what the visualization showed and how they understood the events, but they were not compelled to revise their constructed pictures according to their recognized differences. This indicated that the experienced variations observed in the visualizations were not strong enough to compel them to change their mental models. Three of these students identified differences between their understanding and the events depicted in the visualization, but addressed different features in their revisions. For example student Sc initially reported that ion size and solute movement were not portrayed as he expected. In his revisions he discussed dissociating NaCl molecules, and did not mention his previously reported differences. Only one student initially reported differences, but later did not make revisions. It is Challenging To Accommodate New Information. Several examples remind us of how challenging it is for students to accommodate new information when they notice variation and to let go of existing misconceptions. For example, seven students recognized that sodium chloride was completely dissociated into ions, but four of the seven had difficulty letting go of their ion pair mental image. As a result, some students separated the ions by a very small distance. For example, student Ar initially thought that atoms in a solution were close together. He observed that the atoms in the visualizations were represented farther apart. When Ar made his revision he drew separated atoms, mixed with atoms closer together. He F



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Metacognitive Skill Limitations

appeared to have difficulty accommodating the separation of atoms in his picture wanting to maintain the formula connection (Figure 4). This is consistent with previous studies

Throughout the findings, it was noticed that students had difficulty letting go of misconceptions and repeatedly retained errors in their pictures. Students who have limited metacognitive knowledge and skills may not only “reach erroneous conclusions and make unfortunate choices”, but they may not have the metacognitive ability to recognize that they are retaining flawed understanding.46 As a result, students who are limited in their ability to recognize how their mental models differ from the visualization models are unable to discern variation in critical features, and this severely limits their ability to learn. This might also account for why some students reported that their mental models matched with what they viewed in the visualizations even though their pictures showed little similarity. The students miscalibrated their abilities due to deficits in their metacognitive skills or they lacked the capacity to distinguish accuracy from error.46

Figure 4. Student Ar’s revised picture of aqueous sodium chloride tested for conductivity. The circles to the right of the picture represent chloride ions that have migrated toward the negative electrode.

by Kelly et al., in which it was noted that students were so connected to the symbolic portrayal of ionic compounds that they seemed to map their atomic level drawings onto the formula.32 Some students had difficulty letting go of ion pairs or molecules and maintained at least one pair or molecule in their representations along with their new representation of separated ions indicating that they were in a transitional state of understanding. Student Cr recognized that the ions were portrayed as separated in the visualization and that water molecules were attracted to the ions. In her revised picture, she represented mostly separated ions, but she maintained one sodium chloride molecule (Figure 5). Through her meta-

Ways of Using Atomic Level Visualizations to Construct Understanding

While examining the transcriptions and pictures constructed before and after viewing the visualizations, categories of ways that students used the visualizations to construct their understanding began to emerge. The following section describes characteristics of students’ visualization use (Table 4). Verification Source. In their click and drag pictures of aqueous sodium chloride made prior to viewing the visualizations, students would emphasize different features to account for what was happening at the electrodes. In the best scenario, visualizations served as a source of evidence. In the worst scenario, students simply identified the representation that matched the visualization without considering why it was more appropriate over their other representation. For example, student Ne discussed how the visualization helped clarify his understanding. Ne: I mean, the only difference... I doubted myself when I was doing the questions and then I did see small errors, like the electrodes. Obviously one is charged and the other is not. Recollection Triggered. Throughout the study, students’ understanding of atomic level events evolved. When students connected their recollection to something viewed in the visualization, they indicated that the visualization refreshed their memory or it served to remind them of concepts they had learned, as in this example:

Figure 5. (A) Student Cr’s revised representation of aqueous sodium chloride tested for electrical conduction with emphasis on events at the positive electrode. (B) Student Cr’s revised representations of events near the negative electrode.

cognitive monitoring, she recognized differences between her understanding and the visualization, but she maintained a connection to her previous understanding indicating that she is in a transitional state of understanding.

Ca: It’s pictures that I have seen my high school chemistry teacher draw on the board so I feel comfortable with that.

Table 4. Characteristics and Definitions of Visualization Use Characteristics Verification Source Recollection Triggered The Imitator It is not what they think they see Short-cuts used in constructing representations a

Students Demonstrating Characteristic, % (n = 24)a

Definitions Visualizations were used as a source of evidence to support whether student maintained or changed pictorial representations. Visualization served as a reminder of forgotten information. Students were able to replicate what they saw in the visualizations without being able to explain the scientific basis for their picture. Students misinterpreted what the visualization conveyed. Students limited the amount of details portrayed in their oral and drawn explanations.

25 29 21 25 100

Students could be coded in more than one category. G



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The Imitator. This characteristic was noticed when a student constructed a click and drag picture that looked nearly identical to the visualization in its portrayal of the concept, but then students had difficulty or were unable to explain their representations. The students may have constructed their representations based on recall of previously seen pictures. Student B described how she tried to recall information from a previous learning tool, but did not seem to retain what she learned. B: I remember from the first video (refers to a pre-lab electronic learning tool on precipitation reactions), that solids form a lattice structure so I drew a lattice. I didn’t use the negative and the positive ions of NaCl, because I thought when they are together it’s a neutral compound, so I just used the ones without the charges indicated on it. But I feel like it’s a polar molecule still. One benefit of imitation is that it may cause students to focus more on the narration to justify the reasoning for the items expressed in their pictures. If visualizations are used in this way, the student may develop a stronger understanding. However, upon seeing that a visualization matches their representation, some students may assume that they do not need to know anything further which may impair the learning process. It Is Not What They Think They See. This characteristic documents how a student misinterprets what they saw or learned from a visualization. Rosenthal and Sanger reported this behavior in their study when they examined common errors students conveyed in their oral explanations of two different visualizations that portrayed an oxidation−reduction reaction.20 They contend that misinterpretation occurs when students incorrectly identify objects or symbols depicted in an animation and may lead to misconceptions if students attempt to apply the misinterpretation to account for chemical behavior.20 In this study, students who exhibited this trait demonstrated confusion when they were being interviewed by asking the researcher for confirmation of what they saw. For example, student H believed that aqueous sodium chloride did not conduct because the gold atoms of the electrode in the visualization did not move. When she did not see any change at the electrode she assumed that aqueous sodium chloride did not conduct, even though the narration clearly stated that aqueous sodium chloride conducted and the student had seen macroscopic evidence verifying that conduction occurred. R: In terms of your prediction, what did you learn that was new from these visualizations? H: Um, that it didn’t conduct? Did that show it not conducting? R: I don’t know. What do you think? H: It didn’t conduct because the gold molecules stayed in the same place, so it didn’t conduct. R: Okay, and the gold molecules are what? H: The conductor? Was it...I think it was a conductor. R: And you expected those would move? H: Yea, when it was conducting. Interestingly student H did not maintain her stance that aqueous NaCl did not conduct. This indicates that her misinterpretation did not have explanatory coherence with her existing thoughts, which led her to self-correct the misinterpretation. There were a variety of examples where students rationalized that what they saw in the visualizations fit with their misconceptions demonstrating the power of the misconception’s explanatory coherence to the learner. Student

Sc discussed evidence that supported his belief that water conducted and not the salt. He observed that the orientations of the water molecules near the electrode showed that opposite charges attract and he believed that the water molecules were responsible for electrical conduction. Student V described how her understanding of aqueous sodium chloride conducting was different from what she had previously pictured. She discussed how electrons tried to “pry themselves off amongst each other,” although none of the visualizations portrayed electrons. Shortcuts Used in Constructing Representations. Every student took measures to represent simplified models of their understanding through their click and drag pictures and/or hand-drawn revisions, although only 10 students specifically admitted that they took the liberty of constructing only the most essential features necessary to represent their atomic level understanding. They reasoned that it would take too long or it would be too much work to construct authentic representations of how they pictured the event. Examples of commonly used shortcuts were students who placed only a few water molecules in the background to symbolize bulk water’s presence, construction of a small square or cube of solid sodium chloride to represent a larger, expansive lattice, representation of one or two water molecules attracted to an ion to represent a hydration sphere, or showed only the simplest whole number ratio of ions. Some students felt that the click and drag tools required too much work on their part and that creating more detailed representations would take too long, yet when students drew revisions by hand, they were still unwilling to draw detailed representations. Two examples of students’ justifying their simplifications: Al: Um, I mean to be honest, I think that this is kind of the closest I could get without spending a great deal of time on each picture, individually. Si: I feel like there would be a lot more of the, the, the Cl’s surrounded by the waters, just all the way around, like every like where with and the H’s too, just everywhere. I mean it would be a lot of work to like drag it over, fill it or surround it with oxygens - or hydrogens - or waters and then do the same thing for chloride with a bunch of them. In general, students who represented very limited details in their revisions often did not make large measured gains in their demonstrated understanding.

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CONCLUSIONS

Transitional Evidence and Metacognitive Challenges

Students have difficulty conceptualizing the particulate nature of matter and misconceptions are difficult for students to let go, but this study sheds light on evidence that supports a transitional state where students begin to merge new ideas gained from recognizing visualization features that are in variance with their existing conceptions. In this transitional state,45 aspects of features observed in the visualization were adapted to fit with previous conceptions. The result was a mixture of explanatory principles that reflected the learner’s struggle to accept a completely new mental model, but it indicated that the student was making progress toward improving their mental model of the atomic level events as they incorporated aspects of the visualization where they identified variance from their mental model. Students often demonstrated imperfect understanding when conveying their new understanding and transitioning between H



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explanatory processes. When students lack knowledge of cognition, they also lack the metacognitive skills necessary for accurate self-assessment and thus they are unable to use the visualizations in ways that are conducive for changing their mental models.46 As a result, the learner is unconvinced that changes are necessary and little improvement is noticed or a mixture of explanations is constructed. Metacognitive monitoring was challenging for students and many were uncomfortable fully elaborating on how their understanding matched or differed from the visualizations. Often students used short-cuts and failed to represent the details of their understanding in both their drawn and oral explanations, which made it difficult to ascertain their depth of understanding.

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS The author wishes to acknowledge that the National Science Foundation under Grant No. 0941203 supported this work. Any opinions, findings, and conclusions or recommendations expressed in this paper are those of the author and do not necessarily reflect the views of the National Science Foundation. I would like to thank Sakip Kahraman for his auditing assistance and Laurie Langdon and Loretta Jones for their editorial suggestions.

Focused on General Characteristics

Another goal of this study was to consider the kinds of visualization attributes that students recognized as varying from their understanding and as a result compelled them to revise their mental models. The findings revealed that most students were influenced by very general characteristics such as the structural features of solid sodium chloride and its lack of conductivity and the general movement of the solute and solvent ions of aqueous sodium chloride during a conductivity test. Students expended less attentional effort on detailed features, such as the vibrational movement of ions in a lattice or the complex network of bulk water molecules interacting with ions in the aqueous salt solution. In some cases, they dismissed these features as unimportant or they represented the presence of a feature that, in the student’s opinion, would take too much effort to properly convey. These decisions affect how students adapt what they see in the visualizations to fit with their understanding and contribute to imperfect understanding and retention of misconceptions or alternative conceptions.

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IMPLICATIONS Providing students the opportunity to evaluate their mental models through passive viewing exercises can be beneficial when it is followed with metacognitive activities that require students to monitor their understanding and reflect on what they have learned. Activities that ask students to compare and contrast their understanding of visualizations help the learner develop ways to critically examine information and develop their metacognitive skillfulness. Their monitoring is also an overt product of the activity that allows instructors to gain insight into what students think and how their understanding varies from the visualizations. Unfortunately, this research demonstrates that it is difficult to truly understand what students know about a concept as they are constantly fitting new ideas together and in essence their understanding is always changing. Students’ explanations help us learn what they think, but explanations are only as good as what students are able to convey. As this research indicates, students’ oral and pictorial explanations are simplifications that may only partially represent how their understanding was affected by the activity.

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Article

ASSOCIATED CONTENT

S Supporting Information *

Overview of visualizations used in the study, tables and additional supporting details that provide further evidence of the influence of visualizations on student learning. This material is available via the Internet at http://pubs.acs.org. I



Article

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