the website and the idea look great overall. But compared to Kahn academy I miss that each test (set of question) is not focused on one single new concept.

When using Kahn academy, the sequencing is basically

1- watch video about 1 new concept you do not already know 2- try to do a bunch of question about that new concept to make sure you master it 3- if not go back to step #1 but if you master it (progress to the next concept)

It feels more like a video game where you unlock level sequentially and it is more fun.