Research as a guide for improving student learning: An example from momentum conservation

This paper describes an investigation of student ability to apply the principle of momentum conservation in one dimension. As part of the investigation, we conducted interviews with students who had completed introductory calculus-based mechanics. We found that some of them attributed special significance to a certain limiting case: An (elastic) collision between a light incident object and an initially stationary massive target. They used their correct prediction of the observable outcome of such a collision to support an incorrect view of momentum. A tutorial designed to help students understand this special case improved their performance on examination questions on more general collisions. The process of developing curriculum based on students´ spontaneous, productive reasoning is illustrated. © 2010 American Association of Physics Teachers.