Why does it go up? The impact of the MARS curriculum as revealed through changes in student explanations of a helium balloon

The Model-Assisted Reasoning in Science (MARS) project created a model-centered, computer-supported sixth-grade science curriculum organized around the theme balance of forces. To help monitor effectiveness during implementation in a public middle school, individual student interviews were conducted after each of the curriculum's three sections. In each interview, students were asked to explain why a helium balloon floats up. This article...