Spaced repetition means reviewing something at widening gaps — just as your child is about to forget it — instead of reviewing it often and evenly. The uncomfortable part is the point: the effort of nearly-forgetting is what makes the memory stick.
At a glance
| The intuition | What actually works |
|---|---|
| Review often so it stays fresh | Review just before it fades, then wait longer |
| If it felt easy, it went well | If it felt easy, little was learned |
| Re-read your notes | Try to recall without looking |
| Cram before the test | Space the same minutes across weeks |
| Study one topic until it's solid | Mix topics within a session |
Start with forgetting
In the 1880s Hermann Ebbinghaus taught himself lists of nonsense syllables and measured how fast he lost them. The resulting "forgetting curve" is steep at first and then flattens: most of what you lose, you lose quickly.
The useful discovery was not the curve but what interrupts it. Each time you successfully pull something back out of memory, the next fall is slower. Recall does not just measure the memory; it changes it.
Why the gaps have to widen
If recall strengthens memory, and each success makes the next fall slower, then the right time to review is later each time. Reviewing on a fixed daily schedule wastes effort on cards that were never at risk.
How much later is a real research question, not a guess. The best answer we have is that the ideal gap scales with how long you need to remember something — roughly ten to twenty per cent of that period. Revising for a test in ten weeks? Gaps of one to two weeks are about right.
That is exactly why your child's cards go 1 day, then 6, then 15, then 38, then 90. And it is why we stop at 90: a KS3 child is assessed each term, so a term is the horizon that matters.
Why easy practice feels productive and isn't
This is the part that surprises most parents, and most children.
Re-reading a page feels good. The words are familiar, nothing snags, and it seems like learning. It is one of the weakest study techniques there is. In a large review of ten common techniques, re-reading and highlighting — the two things nearly every child does by default — came out low value. Self-testing and spacing came out top.
The reason is that fluency is not knowledge. Recognising the answer when you see it is a much easier task than producing it from nothing, and only the second one predicts whether your child can do it in an exam hall.
What this looks like on the screen
Your child sees one card. They try to answer before revealing it — that attempt is the whole mechanism. Then they see the answer and pick one of three buttons: Tricky, Got it, Too easy. Their choice sets the next gap.
Two design decisions follow from the research:
- Getting it wrong is not a penalty. A Tricky card comes back within the same session and again tomorrow, and its future gaps stay shorter for good. Nothing is deducted, nothing is reported to you as a score. If a child feels judged for pressing Tricky they will stop pressing it honestly, and then the schedule is built on a fiction.
- The day's queue is capped at 20 cards. A session must be finishable. An unbounded queue becomes a debt, and debts get abandoned.
What it does not do
Spaced repetition is for things with a recallable answer: a definition, a rule, a formula, a step. It is not a substitute for working through whole problems, writing an essay, or doing an experiment. If someone tells you flashcards can replace practice, they are overselling.
Nor does it help if the cards are bad. A card holding three facts at once cannot be graded honestly, which is why ours are written by the tutor and held to one fact each.
FAQ
What is spaced repetition in one sentence?
Reviewing something at widening intervals — just as you are about to forget it — rather than reviewing it often and evenly.
Isn't more practice always better?
No. Practice that feels easy because the material is still fresh does very little. The effort of nearly-forgetting is what strengthens the memory, which is why the gaps deliberately grow.
Does spaced repetition work for maths, or only vocabulary?
It works for anything with a recallable answer, including definitions, rules, formulas and worked steps. It does not replace practising whole problems — see our article on maths flashcards.