This is a pretty interesting paper up to the end of page four. It discusses the phenomenon of 'conditional release of material' - that is, showing students course content only after they have reached a certain threshold, such as passing a quiz. The author surveys types of and conditions for conditional release. You can stop reading at the point where you read the statement "Two of the authors surveyed undergraduate students in their courses over two semesters." The data that follows is essentially useless, even discounting the response rate of 38% from the surveys (I don't know why authors feel compelled to write these papers and why journals like JOLT feel compelled to publish them).