[zpr]

FYI, if you are interested in the gramatical explanation of a level, you could log into the web version of Duolingo (your same account will work) and they are all there for many languages, as well as several other features (depending on the language) such as a full dictionary of words you've studied, and each has its own "health bar". There are also flash cards although now Duolingo has a separate app for that called TinyCards.

I'm not affiliated with them in any way but with the number of people I've convinced to use it, I should be getting commission.