Many platforms such as Memrise and Anki have spaced repetition ( https://en.wikipedia.org/wiki/Spaced_repetition ) features for flashcards. That is, over time, the flashcards with content that the user has responded to successfully are presented less and less frequently, while cards that the user struggles with continue to be presented regularly. Unfortunately, these platforms tend to be quite limited in terms of response types.
On the other hand, many quizbuilder platforms, such as yours, allow teachers to design test items with a wide variety of response types. As far as I can tell — I have looked far and wide — there are no sites that bring these two types of functionality together.
Specifically, I would like to see an option for spaced repetition of individual items within and across quizzes. So, within a given quiz, a item that is responded to incorrectly would show the correct answer and then reappear within the quiz after a brief pause (following a typical spaced repetition schedule). And across quizzes, if a student takes three quizzes on Monday, they would have the option to review/redo the incorrect items from all three quizzes in a single session on a spaced repetition schedule.