This paper argues that first time eLearners often experience cognitive overload, (as described in Cognitive Load Theory), in the early stages of an online course and it is suggested that this is a likely contributor to high drop out rates, particularly in terms of those withdrawing within the first few weeks of the course start
For those looking for a quiz/test tool, classmarker might be one that you could try out. I've used classmarker for about 5 years now, and I really like the many options it has. The ability to make question banks quite easily, and re-use quizzes/tests over and over again for different groups makes it really nice if you are teaching the same classes again and again. It can be a bit complex with all the different settings/tools/options/etc. but I think you will find it useful and easy to use if you are looking for a powerful quizzing/testing tool.