As with the use of flash cards, one should have the option of pulling a card from the top of a randomly stacked deck. At that point the student should be able to place the card into at least 2-3 piles based on how well they knew the answer. After that the cards that are well know would come up less frequently. This would be in line with research on retrieval practice and would line up with flash card programs like Anki. It would make this SO much more useful!