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 with 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 that identify which correct and incorrect knowledge components students have 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

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

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.

Dependent Variables

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.

Independent Variables

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

For instance, in one study 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, text is identical in both conditions and the diagram condition supplements the text with pictures.

Hypothesis

Presenting visual representations along with textual explanations during instruction and problem solving will lead to a deeper, more conceptual understanding of chemistry concepts as measured by improved performance on conceptual multiple choice and scaffolded problem solving items and promote robust learning as measured by performance on open-ended transfer questions.

Findings

Microscopic Level
Does problem representation influence the retrieval 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.

Macroscopic Level
To date, results suggest no advantage for the addition of visual representations. 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. To date, three studies (2 in vivo at UBC and CMU and 1 lab study at CMU) have been run using tutorials on acid and bases and buffer solutions (types of equilibrium systems). While participants in each study showed significant learning gains from pre to posttest, no study has shown a selective learning advantage when diagrams are present.

As the pattern of results was similar in each study, figures from the CMU lab study are shown.

Explanation

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 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. If an effect it found, our hypothesis is that the practice of linking abstract notations (in equations) to representations that depict individual molecules helps students develop a deeper, more conceptual understanding of chemistry.