Retrieval practice
Today's review
Cards the schedule says you are about to forget.
Every question you answer anywhere on this site enters an SM-2 spaced repetition schedule. A card you got right and were sure about comes back in four days, then ten, then twenty-five. A card you got wrong comes back tomorrow, and its ease drops slightly — but only slightly, because one bad day should not bury a card you actually know.
The queue is sorted most overdue first, ties broken by most lapses, and it is global rather than per chapter. That is deliberate: a session naturally mixes window functions with deadlocks with backup strategy. Interleaving is harder, it retains better, and it is exactly what an interview does to you.
The “I half-guessed” button is the only signal the scheduler cannot work out for itself. A right answer you had to dig for is not the same memory as one you knew, and scheduling them identically is why so many flashcard apps stop working after a month.