In a recent study we showed that physics students' problem-solving performance can depend strongly on problem representation, and that giving students a choice of problem representation can have a significant impact on their performance [ P. B. Kohl and N. D. Finklestein, Phys. Rev. ST. Phys. Educ. Res. 1, 010104 (2005) ] In this paper, we continue that study in an attempt to separate the effect of instructional technique from the effect of content area. We determine that students in a reform-style introductory physics course are learning a broader set of representational skills than those in a more traditional course. We also analyze the representations used in each course studied and find that the reformed course makes use of a richer set of representations than the traditional course and also makes more frequent use of multiple representations. We infer that this difference in instruction is the source of the broader student skills. These results provide insight into how macrolevel features of a course can influence student skills, complementary to the microlevel picture provided by the first study. (Contains 21 endnotes, 4 tables and 6 figures.)