One of my frustrations with it was that if they pass a unit, it might (or might not) stay there for further practice, but after a few days it is gone for good and you can't go back. I don't know why they can't have a list of topics completed and you can click on it to do it again later. But they don't, as far as I can tell. Which reminds me, I think that I'm going to cancel our subscription and maybe pick it up again next summer. It seems like it's good for the lower grades (maybe up through 5th or 6th grade material)...after that it kind of fizzles, I think, getting more bizarre in terms of how the concepts are taught. For certain topics, you really need more than pictures in order to understand. It might be good for reviewing concepts, but then the lessons drag on forever--much longer than what would be needed.