I've only had a quick look at this report, so I can't say much about it. But still, I thought maybe someone might want to read it. It's a very interesting and quite comprehensive study of the students' response to an E&M test after going through two different curricula for intro E&M class. Not only that, they monitored this at four major universities - Purdue, North Carolina State, Georgia Tech, and Carnegie Mellon - resulting in a very extensive survey.
Abstract: The performance of over 2000 students in introductory calculus-based electromagnetism (E&M) courses at four large research universities was measured using the Brief Electricity and Magnetism Assessment (BEMA). Two different curricula were used at these universities: a traditional E&M curriculum and the Matter & Interactions (M&I) curriculum. At each university, post-instruction BEMA test averages were significantly higher for the M&I curriculum than for the traditional curriculum. The differences in post-test averages cannot be explained by differences in variables such as pre-instruction BEMA scores, grade point average, or SAT scores. BEMA performance on categories of items organized by subtopic was also compared at one of the universities; M&I averages were significantly higher in each topic. The results suggest that the M&I curriculum is more effective than the traditional curriculum at teaching E&M concepts to students, possibly because the learning progression in M&I reorganizes and augments the traditional sequence of topics, for example, by increasing early emphasis on the vector field concept and by emphasizing the effects of fields on matter at the microscopic level.
Edit 10/5/09: This exact reference to this paper is: M.A. Kohlmyer et al., Phys. Rev. ST Phys. Educ. Res. v.5, p.020105 (2009).