[ddffre]

I highly recommend using flashcards apps, especially this one that I have found. As mentioned in the article about quizzes, this app has just that.

https://play.google.com/store/apps/details?id=flashcards.wor...

[bemmu]

For those studying Japanese, this one is amazing: https://nihongo-app.com/

It has sets for all Japanese school grades, split into daily chunks so that you can keep going forward with the app for years.

The only thing missing is kanji stroke orders, but the dev has hinted that those would be coming soon.