While analyzing effects of the flipped classroom style, researchers controlled for potential differences (due to student perception, learning model, context, etc.) Students were asked to report their perception of collaborative learning on a scale in order to make accurate comparisons between the two groups. The scale was validated by experts to ensure that it was measuring the intended dimensions. Students in the flipped classroom model used a blog to access course materials. Each topic session had roughly as much individual work as collaborative work in the classroom. Work outside the classroom consisted of conceptual maps, presentations, blog posts, and shared folders.