  In this meta-analysis, we synthesize the results of 24 studies using the
Colorado Learning Attitudes about Science Survey (CLASS) and the Maryland
Physics Expectations Survey (MPEX) to answer several questions: (1) How does
physics instruction impact students' beliefs? (2) When do physics majors
develop expert-like beliefs? and (3) How do students' beliefs impact their
learning of physics? We report that in typical physics classes, students'
beliefs deteriorate or at best stay the same. There are a few types of
interventions, including an explicit focus on model-building and/or developing
expert- like beliefs that lead to significant improvements in beliefs. Further,
small courses and those for elementary education and non-science majors also
result in improved beliefs. However, because the available data oversamples
certain types of classes, it is unclear whether these improvements are actually
due to the interventions, or due to the small class size, or student population
typical of the kinds of classes in which these interventions are most often
used. Physics majors tend to enter their undergraduate education with more
expert-like beliefs than non-majors and these beliefs remain relatively stable
throughout their undergraduate careers. Thus, typical physics courses appear to
be selecting students who already have strong beliefs, rather than supporting
students in developing strong beliefs. There is a small correlation between
students' incoming beliefs about physics and their gains on conceptual
mechanics surveys. This suggests that students with more expert-like incoming
beliefs may learn more in their physics courses, but this finding should be
further explored and replicated. Some unanswered questions remain. To answer
these questions, we advocate several specific types of future studies.
