I was thinking about this alot lol well a bit more. There could be a page or mebe a link on the lesson pages for the tests. Since the lessons are sort of short [but very informative n_n] maybe be kinda like, Lessons 1-3, then 3-6, or in different variations so you have it kind of challenging or maybe the examination to a single lessons would be good. I know people are at different levels so maybe it can be sort of like a text book review test, wich has all the answers on the material you have read. The general test would be also good to see in what areas you need more to study on.