  Previous research indicates that after standard instruction students at all
academic levels often construct a conceptual framework in which the ideas of
absolute simultaneity and the relativity of simultaneity co-exist. This article
describes the development and assessment of instructional materials intended to
improve student understanding of the concept of time in special relativity, the
relativity of simultaneity, and the role of observers in inertial reference
frames. Results from pretests and post-tests are presented to demonstrate the
effect of the curriculum in helping students deepen their understanding of
these topics. Excerpts from taped interviews and classroom interactions help
illustrate the intense cognitive conflict that students encounter as they are
led to confront the incompatibility of their deeply-held beliefs about
simultaneity with the results of special relativity.
