gabelschlager

It doesn't even need to be that complicated. Starting out with good software that tracks exercise progress of the students, giving them exercises on a suitable level and immediate feedback would already go a long way. And teachers could use it to see, how the students perform and know what to teach in more detail.

I think ProtonMail is as safe as it gets without setting up your own mail server. Their software is open source and they regularly perform security audits.

I'm curious about the space repetition algorithm you've used. Is it based on SM-2 like Anki, a ML solution or something else.

Other than that, I've played around with the site a bit and it delivers what it promises upon. Though the UI is a bit simplistic in a few places.