"On the contrary- they are cards containing questions which you must answer. The idea is that the cards are quickly revealed, one at a time, and the answer given just as quickly.

"In the end, it forces the mind to try and recall the correct answer at a quicker speed, making it easier to remember the answer at all. So, for example.

"We could create cards with the symbols on the Periodic table- when a card is shown, you would immediately call out what you think the answer is, and you would find out if you were correct or not. If not, it is added to the deck once more, and eventually, cards remaining in the deck are run through again.

"It is apparently an extremely useful way of remembering things such as this."