Every concept has two tabs: Learn (the lesson) and Test. The Test tab turns the concept's key points into flashcards and uses spaced repetition to help them stick, so you spend your time on what you are about to forget, not on what you already know.

How spaced repetition works

You review a card, then tell the app how well you remembered it. Cards you find hard come back soon; cards you know well come back less and less often, stretching out over days and weeks. That expanding schedule is the whole trick: reviewing right before you would forget is what moves something into long-term memory with the least effort.

Because the schedule has to be remembered across days, your progress is tied to your account, so testing works best when you are signed in.

A review, step by step

  1. Open a concept and click the Test tab (or go to Review for all concepts at once).
  2. You will see how many cards are ready. Click Start review.
  3. Read the question and try to recall the answer in your head.
  4. Click Show answer, then rate yourself:
    • Again: you forgot it (it comes back next time).
    • Hard: you got it, but it was a struggle.
    • Good: you recalled it.
    • Easy: it was effortless.
  5. Your rating sets when that card is next due. Keep going until the deck is done.

Some cards are interactive. You might be asked to type an answer or hear an example played, but you always finish by rating yourself. The rating is what drives the schedule; the interactive part is just there to help you.

When you are caught up

If nothing is due, you are caught up. Come back another day and the due cards will be waiting. You can still press Practice anyway to run through the deck for fun; practising never changes your schedule.

Your own cards

On any concept's Test tab you can add your own cards, with your own question and answer, and they will be mixed into that concept's reviews alongside the built-in ones. Your cards are private to you. You can edit or delete them any time under Your cards.

The Review area: everything in one place

The Review page (the Test yourself button on the Concepts page) pools the due cards from every concept into a single queue, leading with whatever you are closest to forgetting. It is the fastest way to do your daily review without hopping between pages. From here you can also:

Trying it without an account

You can take any deck for a spin while signed out, reading the cards and rating them, but nothing is saved, so the spacing cannot carry over to your next visit. Sign in to keep your progress and to add your own cards.