When mold grows on bread in a sealed bag, does the system's mass increase? Nearly 60% of U.S. middle-school students would incorrectly say yes, although in fact, chemical reactions rearrange but do not increase the number of atoms inside a bag of bread as mold forms.
A new middle-school curriculum, developed by Project 2061 at AAAS, shows promise for overturning such persistent student misconceptions about science. When teachers field-tested the new curriculum, their students were better able to correctly explain everyday phenomena that involve chemical reactions, from the rusting of an iron nail to the growth of a human baby. Project 2061 Senior Research Associate Cari Herrmann-Abell reported that conclusion , based on field-test findings, on 31 March during the National Association for Research in Science Teaching (NARST) annual conference.
In a previous test , the Project 2061 curriculum, Toward High-School Biology: Understanding Growth in Living Things, clearly helped to improve students' understanding of key science concepts-such as how food undergoes chemical reactions that break down and rearrange atoms to form new molecules, supporting growth. More recently, seven middle-school teachers, including four first-time users of the curriculum, were able to boost their students' test scores, compared with students in a control group that used their school district's typical curriculum.
By presenting chemistry and biology ideas in an integrated fashion, the new unit reflects the National Research Council's conclusion that "much of modern biology has become increasingly chemical in character," and moves beyond the traditional middle-school experience, in which students tackle physical science and life science concepts separately. "The new curriculum shows students how chemical processes happen in both living and non-living systems," explained Jo Ellen Roseman, director of Project 2061 and principal investigator for the curriculum development study.
Before-and-after tests completed by 674 students working with novice as well as experienced teachers revealed a "significantly positive correlation" between the Project 2061 curriculum and gains in understanding the targeted science ideas, said Herrmann-Abell. Students who experienced the unit also "held fewer misconceptions and were better able to use science ideas about atoms and molecules to explain real-world phenomena," she added.
As an example, prior to instruction, about 31% of students in "control" classrooms using traditional curriculum and 33% of students in classrooms using the new unit incorrectly suggested that chemical reactants are transformed into different types of atoms during a reaction. Over the course of six weeks, however, students using the new unit engaged in lessons in which they used LEGO® bricks and ball-and-stick models to model a variety of chemical reactions. In this way, they saw for themselves that although atoms regroup during the process, the product molecules are always made from the same number of each type of atoms as the reactant molecules. After instruction, only 14% of the students using the new curriculum, compared with 23% in the control group, still seemed to have misconceptions about the transmutation of atoms.
The Project 2061 curriculum, which is being developed in partnership with the curriculum study group BSCS in Colorado Springs, is supported by a grant from the U.S. Department of Education's Institute of Education Sciences and encompasses instructional materials for students as well as teachers, plus face-to-face and online professional development materials. The paper presented at NARST was co-authored by Roseman, Herrmann-Abell, and Jean C. Flanagan, formerly a Project 2061 research associate.
"Our goal is to help provide students with a better foundation for learning modern biology as well as basic chemical concepts," Roseman said. "We continue to feel encouraged by the results of our research."