<qa>  How many study arms were randomized to students?This study involved medical students from seven US medical schools participating in a trial of two WISE-MD computer-based learning modules. Students were randomized to 1 of 4 study arms. The 4 content-equivalent conditions were: screen shots with voiceover and no interactivity; learner control of pacing through multi-media content; social networking features; and social networking features plus user interface enhancements. 