Visual Representations in Science Learning

Visual Representations in Science Learning

Jodi Davenport

Abstract

Visual representations, in the forms of diagrams, notation (e.g., equations), graphs and tables are fundamental tools in science instruction and practice. Whether diagrams or notational systems are helpful aids to problem solving depends critically on the content of the visual representation and how learners are able to process the information they contain. Expert/novice studies have demonstrated that different levels of experience result in differential processing of the same stimuli. However, it is not known how students are able to refine initially shallow understandings into meaningful chemical concepts or how the coordination of multiple representations helps with this process.

The current project seeks to determine when and how the use of multiple representations during instruction and problem solving will lead to robust learning. To date, 7 studies (4 completed, 3 ongoing) have explored science learning at the two levels (micro and macro) of the theoretical framework.

Microscopic Level: Identifying knowledge components and developing assessments In order to assess robust learning, we conducted studies and collaborated with Chemistry and Education faculty (David Yaron, Gaea Leinhardt & Jim Greeno) to identify key knowledge components of equilibrium and acid base chemistry. For instance, a verbal protocol study has demonstrated that experts and novices differ in their ability to invoke relevant knowledge components in contexts involving different representations (e.g., chemical equations, graphs, and diagrams). We continue to create and revise new forms of assessments of knowledge transfer that identify which correct and incorrect knowledge components students have and apply as they learn chemistry.

Macroscopic Level: Testing general learning principles At the macroscopic level, in vivo studies test general learning principles. Studies have investigated whether the use of molecular-level diagrams increases robust learning as measured by transfer performance and have manipulated conditions to determine what type of instructional prompts will promote active processing. Early studies failed to find a learning advantage for molecular level diagrams and ongoing studies seek to determine what conditions may be required to produce a benefit of multiple representations during instruction.

Glossary

Visual representations: External representations that are used in instruction and problem solving such as diagrams, graphs, and equations

Hypothesis

Chemical equilibrium is a difficult topic for students to learn as it involves learning a large set of knowledge components and applying these components flexibly in a variety of situations. As different representations make salient different key features of knowledge components, we hypothesize that instruction that requires the coordination of multiple representations will lead to more robust learning as measured by transfer tests such as conceptual multiple choice questions and open-ended inference questions.

Research Questions

Our project seeks to identify the knowledge components of equilibrium and acid base chemistry and determine when and how different types of representations lead to the acquisition of correct knowledge components leading to robust learning.

• What are the knowledge components of equilibrium and acid/base chemistry? (CMU, lab study #1, 2006; Chemistry working group)
• How do experts and novices differ in equilibrium problem solving with multiple representations? (CMU, lab study #1, 2006)
• Does the presence of molecular level diagrams enhance robust learning of acid/base chemistry? (UBC, in vivo study #1, 2006; CMU, in vivo study #2, 2006)
• Do molecular level diagrams enhance self explanation leading to robust learning in a tutorial on acids and bases? (CMU, lab study #2, 2006)
• Do labelled diagrams enhance robust learning as measured by transfer performance? (UBC, in vivo study #3, 2007; CMU, in vivo study #5, 2007)
• Do virtual lab activities (in which multiple representations must be coordinated) enhance performance on interactive problem solving and transfer questions? (UBC, in vivo study #3, 2007)
• Does instruction with multiple representations including molecular level diagrams and graphs enhance the acquisition of equilibrium knowledge components leading to robust learning? (CMU, in vivo study #4, 2007)

Background and Significance

Robust learning in chemistry is more than learning a set of facts or procedures. Instead, many pieces of knowledge must be acquired and flexibly coordinated in order to make predictions, inferences and analyses of chemical systems. We chose to focus on chemical equilibrium systems as the knowledge is important for understanding processes in chemistry, biology and engineering and the domain is notoriously difficult for students (e.g., Banerjee, 1991; Van Driel et al. 1999).

As the knowledge components of chemical equilibrium are not necessarily explicit in textbooks or instructional materials, we have formed a Chemistry working group with Chemistry, Education and Learning Science faculty to identify core pieces of understanding in this domain. In addition, verbal protocol analyses help us understand student how students process instruction and solve chemistry problems.

Our hypothesis is that instruction and practice that includes a variety of representations will lead to robust learning. Multimedia instruction is widely believed to help chemistry learning by providing a bridge between the mathematical procedures and core chemistry concepts. For instance, chemistry education researchers have suggested that the ability to transform between representations leads to increased success in problem solving (Bodner & Hunter, 2000) and that including diagrams during classroom instruction leads to improved conceptual understanding (Ardac & Akaygun, 2004; Bunce & Gabel, 2002; see Kozma & Russell, 2005 for a review; Noh & Scharmann, 1997; Sanger & Badger, 2001; Williamson & Abraham, 1995). Though the results of classroom studies are promising, the interventions often lasted many class periods and the content in the experimental and control classes was not tightly controlled, so it is unclear exactly how specific representations influenced learning. Further, assessments that demonstrated greater conceptual understanding did not always show increased problem solving performance.

In a number of laboratory studies, Mayer (Clark & Mayer, 2003), Ainsworth & Loizou (2003) and others have found that instructional materials that include both diagrams and text provide learning benefits over materials that only include text. Will this same learning advantage extend to classroom-based instruction? Studies in chemistry education research have suggested that molecular level diagrams may promote deeper understanding that text or equations. However, these classroom-based studies lacked rigorous controls and assessments of robust learning. The current project investigates if and when the presence of visual representations in addition to text promotes deep conceptual understanding in chemistry.

Independent Variables

The studies in the project manipulate the presence of visual representations in chemistry instruction and problem solving.

For instance, in the (CMU, 2006) Lab Study #1, experts and novices solved problems in diffferent representational formats. The traditional format, found in many textbooks, involves a chemical equation and text-based setup. The diagram format requires solvers to additionally integrate pictorial information.

In studies testing the role of molecular-level representations in chemistry instruction (Lab Study #2, in vivo Studies #1, #2, #3 and #5), text is identical in both conditions and the diagram condition supplements the text with pictures.

Dependent Variables

Transfer Questions
Our studies use a range of transfer assessments

• Conceptual Multiple Choice
  • E.g. You have 5 weak acids in your laboratory and want to create a series of buffer solutions. If the target pH is 4.3 which weak acid you would use to create your buffer, and would you should have more weak base, weak acid or the same amount of each?

Weak acid A pKa = 7.35

Weak acid B pKa = 7.15

Weak acid C pKa = 6

Weak acid D pKa = 4.3

Weak acid E pKa = 6.5

• Open-ended Transfer Questions
  • E.g., "How could you make a solution of lemon juice that is more acidic than a solution of hydrocholoric acid?"
• Scaffolded Problem Solving with tutors
• Virtual Laboratory Problems

Normal Assessments
Include:

• Definitions: Defining terms such as acid/base
• True/False questions

Dependent variables include improvement from pre to post test on conceptual multiple choice questions, performance on scaffolded problem solving with tutors and performance on open-ended transfer questions.

Findings

Expert/Novice Equilibrium Problem Solving: Lab study #1

N = 16 (CMU, 2006) Lab Study #1

The two aims of this study were 1) to create a taxonomy of knowledge components for equilibrium chemistry and 2) to determine whether problem representation led to differences in application of knowledge components.

A knowledge decomposition was carried out on the transcribed protocols and a taxonomy of equilibrium knowledge components has been created.

Findings Summary

To assess whether problem representation influenced the application of knowledge components, experts and novices solved equilibrium problems in different contexts while talking aloud. While experts were equally able to retrieve the correct knowledge component (in this case that the equilibrium constant, K, was required for problem solving), novices were able to retrieve the correct knowledge component when solving a traditional problem, but were less successful on problems using molecular-level diagrams. There was a significant main effect of expertise, F(1,13) = 9.15, p = .01, and an interaction between expertise and problem type, F (1, 13) = 5.205, p = .04.

Learning with molecular level diagrams: In vivo studies #1 and #2

N = 42 (UBC, 2006) in vivo Study #1
N = 89 (CMU, 2006) in vivo Study #2

The aim of these studies was to determine whether molecular level diagrams lead to increased performance on tranfer questions after reading a tutorial that either contained Text+Diagram, or Text Only.

Results (UBC, 2006) in vivo Study #1

• An ANCOVA was run on posttest scores with format (Diagram+Text vs. Text Only) as a between-subjects variable and pretest scores as a covariate. No significant effect of condition was found, F(1, 39) = .025, p = .88. Posttest scores were similar regardless of whether students were in the diagrams (M =.72) or text-only (M = .72) conditions.

Results (CMU, 2006) in vivo Study #2

• A mixed 2x2 ANOVA was carried out with format (Diagram+Text vs. Text-only) as a between-subjects variable, time of test (Pre vs. Posttest) as a within-subjects variable and multiple-choice accuracy as the dependent variable. Pretest to posttest gains were significant, F(1, 87) = 94.4, p < .001, but there was no effect of format, and no interaction between test-time and format. See table below.

Findings summary

To date, results suggest no advantage for the addition of diagrams to text. Specifically, acid/base chemistry tutorials that included molecular-level diagrams did not produce enhanced learning compared with text-only versions of the same tutorials. Future studies will investigate whether labelled diagrams will be more likely to promote integration of textual material with visual representations, leading to more robust learning of chemistry concepts.

Molecular level diagrams and self explanation: Lab study #2

N = 22 (CMU, 2006) Lab Study #2

Figures from the CMU lab study are shown.

Learning from labelled molecular level diagrams and Virtual Lab activities: In vivo study #3, UBC, 2007

N = 1139 (UBC, 2007) in vivo Study #3

The influence of multiple representations on knowledge component acquisition in chemical equilibrium: In vivo study #4

N = 172 (CMU, 2007) in vivo Study #4

Molecular level diagrams and robust learning of acid base buffer concepts: In vivo study #5

N = 172 (CMU, 2007) in vivo Study #5

Explanation

The knowledge decomposition of chemical equilibrium has revealed a number of correct knowledge components to be acquired by students and incorrect knowledge components to be avoided. This taxonomy has been used to create assessments used in our studies.

Our expert-novice protocol study revealed that experts are more likely to invoke a relevent knowledge component across different problem types than novice solvers. This result suggests that many students maintain a shallow understanding of chemical systems even after completing a year of college-level chemistry. Current studies are addressing whether instruction that ties the core concept of progress of reaction (identified through the expert/novice studies) to multiple representations will lead to more robust learning.

Our studies testing learning benefits for visual diagrams during instruction suggest the large effects of diagrams commonly found in laboratory studies of topics such as bicycle pumps, lightning formation and disc brakes may be difficult to replicate in educational settings. Active and intentional coordination of representations may be required if diagrams are to increase learning and the mere presence of diagrams does not guarantee this type of active processing. Current studies seek to determine whether labelled diagrams will enhance the coordination of text and diagrams via sense making. Further, prior work has not closely mapped the features of to-be-learned material to the information contained in diagrams and text. In our ongoing studies, we are investigating which pieces of information are contained in text, which are contained in the diagrams and which features students are able to extract when they are presented with multiple representations.

Publications and Presentations

Davenport, J.L., Klahr, D. & Koedinger (2007). The influence of diagrams on chemistry learning. Paper accepted for the 12th Biennial Conference of the European Association for Research on Learning and Instruction. August 2007.

Davenport, J.L., Klahr, D. & Koedinger (2006). The influence of external representations on chemistry problem solving. Poster presented at the Forty-seventh Annual Meeting of the Psychonomic Society in Houston, Texas. November 2006.

Yaron, D., Karabinos, M., Davenport, J. & Leinhardt, G. Virtual labs and scenario-based activities for introductory chemistry. American Chemical Society - Penn-Ohio Regional Meeting, Theil College, Greenville, PA, October 2006.

Yaron, D., Karabinos, M., Davenport, J. & Leinhardt, G. Virtual lab activities for introductory chemistry labs, American Chemical Society Annual Meeting, San Francisco, September 2006.

Yaron, D., Karabinos, M., Davenport, J. & Leinhardt, G. Virtual labs activities for introductory chemistry. Biennial Conference on Chemical Education, Purdue University, West Layefette In, July 2006.

Yaron, D., Karabinos, M., Davenport, J., Cuadros, J., Rehm, E., McCue, W., Dennis, D., Leinhardt, G. and Evans, K. The ChemCollective Virtual Lab and Other Online Materials. Presented at Duke University, Durham, NC, November 2005.