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Results from a Pilot Study of a Curriculum Unit Designed to Help Middle School Students Understand Chemical Reactions in Living Systems.

Students often have trouble understanding key biology ideas because they lack an understanding of foundational chemistry ideas. AAAS Project 2061 is collaborating with BSCS in the development a curriculum unit that connects core chemistry and biochemistry ideas in order to help eighth grade students build the conceptual foundation needed for high school biology. The unit is designed to engage students in (a) observing phenomena that are explicitly aligned to the targeted ideas and selected to address common learning difficulties and (b) using models to help them interpret the phenomena in light of the targeted ideas. The unit was pilot tested with students from an urban school and a suburban school in the mid-Atlantic region of the U.S. at the end of or just after eighth grade. Multiple choice pretests and posttests were used to measure the change in students’ understanding. The pre/posttest data were analyzed using Rasch modeling and the racking and stacking methods. The stacking method showed that the students at both schools made statistically significant gains in their performance on the items testing understanding of the targeted chemistry and biochemistry ideas. The racking method showed that the difficulty of most of the items decreased as a result of the intervention, suggesting that the unit successfully targeted most of the chemistry and biochemistry ideas. A distractor analysis showed that the students appeared to hold fewer misconceptions after participating in the unit. These results were used to inform revisions to the curriculum unit.