Designing Assessments to Track Student Progress in Understanding the Complex Roles of Energy in Photosynthesis

• In Event: Assessment of Complex Thinking in Mathematics, Reading, Science, and History

Abstract

Understanding photosynthesis requires students to integrate the complex roles of energy with observable aspects of plant growth (American Association for the Advancement of Science, 1993). Yet assessments often focus on isolated facts about reactants and products of photosynthesis rather than students’ integrated understanding of how energy is involved in photosynthesis.
To more accurately assess students’ progress in science, we designed two new item types following the knowledge integration framework (Linn, et al., 2006; Liu, et al, 2008). These new item types, Energy Stories and MySystem, capture the links among ideas. For example, for photosynthesis Energy Stories require explanatory narratives linking energy sources, energy transformation, energy storage, and energy transfer. MySystem diagrams allow students to illustrate how energy flows between objects using icons and arrows (Figure 1). These new assessments capture students’ repertoire of ideas and provide more details about the coherence of ideas than typical assessments.


Figure 1. MySystem Interface
(the figure could not be displayed in the paper summary but it is displayed in the full session summary document).

In this study, we show how the new assessments capture progress in student learning from pretest to posttest. Two middle school teachers taught the Web-based Inquiry Science Environment (WISE) photosynthesis unit to 270 seventh grade students for 12 days. Students generated pre- and post-project Energy Stories and MySystem diagrams about how energy is involved in photosynthesis.
The results show that students improved significantly in understanding the complex roles of energy in photosynthesis and in making scientifically valid connections between energy concepts. The results help diagnose the nature of this progress and shed light on gaps in student knowledge. Compared to students’ responses to typical explanation items, Energy Stories show how students link observable and cellular processes to explain where plants get energy to grow, how energy is transformed, and where energy goes. The Energy Stories show how students reinterpret prior knowledge and build on their energy ideas. They provide specific examples of connections between energy ideas, such as how plants use light energy from the sun to start chemical reactions and how molecular processes of energy transformation happen in the chloroplast. The MySystem diagrams provide a detailed representation of connections between energy sources, energy transformations, and energy transfer. Energy Stories and MySystem assess complementary aspects of students’ understanding of a complicated process of photosynthesis. By comparing performance across these two item types, we can validate the coherence of student understanding.
These findings show the importance of using multimodal assessment tools to capture how students integrate ideas. They provide a useful diagnostic tool for both teachers and researchers.

Authors

• Kihyun (Kelly) Ryoo, University of North Carolina - Chapel Hill

• Marcia Linn, University of California - Berkeley