For interesting research on the value of computer-assisted/on-line learning go to
http://www.thencat.org/PCR/R1Lessons.html

SUMMARY
Here are some extracts from this website:

• Continuous Assessment and Feedback. Six of the projects incorporated automated (computer-based) assessment and feedback into their redesigns. Automating assessment and feedback enabled both repetition (student practice) and frequent feedback, pedagogical techniques that have repeatedly been documented to facilitate learning. Students were regularly tested on assigned readings and homework using short quizzes that probed their preparedness and conceptual understanding. These low-stakes quizzes motivated students to keep on top of the course material, structured their studying and encouraged them to spend more time on task. Online quizzing encouraged a "do it till you get it right" approach: students were allowed to take quizzes until they mastered the material.

Quizzes also provided powerful formative feedback to both students and faculty members. Faculty could detect those areas where students were not grasping concepts, thereby enabling corrective actions to be taken in a timely manner. Students received diagnostic feedback that pointed out why an incorrect response was inappropriate and directed them to material that needed review. Since students were required to complete quizzes before class, they were better prepared for higher-level activities in class. Consequently, the role of the instructor shifted from one of introducing basic material to one of reviewing and expanding what students had already mastered ...

Online Tutorials. UW and Virginia Tech were the most sophisticated users of online tutorials. Building on substantial experience in using and developing interactive materials, UW has developed thirty-seven Web-based instructional modules in chemistry as of July 2001. Each tutorial module leads a student through a topic in six to ten interactive pages. When the student has completed the tutorial, a debriefing section presents a series of questions that test whether the student has mastered the content of that module. UW also incorporated interactive chemistry materials created by Stanley Smith at UIUC. Students found these online tutorials to be very helpful; they particularly liked the ability to link directly from a problem they had difficulty with to a tutorial that helped them learn the concepts needed to solve the problem. Many reported that they found the online material much more accessible than the textbook.