How to make an algorithm for memorizing words?

Question

Algorithms

Hello! I want to write a site for learning English words, like lingvist, maybe someone knows. So, I want to make some kind of algorithm so that these words do not appear randomly, but with some kind of systematicity. For example, if they have already come across a couple of times, they will come across less often. In short, tell me how to make an algorithm for the appearance of words?

Answer 1

https://en.wikipedia.org/wiki/Spaced_repetition
Implemented for example in Anki. You can see the code.