Review algorithm
Spaced repetition
Memory works such that forgetting begins the moment you meet a new word, and every successful recall slows it down. Spaced repetition catches a word just as it is about to slip away: that is where a review does the most good, while an earlier one does almost nothing.
Recalling beats re-reading
Looking at a word next to its translation creates a feeling of knowing — but that is recognition, not command of it. What leaves a real trace is effort: trying to produce the meaning yourself before it is shown. That is why learning here is built on exercises rather than on scanning lists.
It also explains why some reviews feel hard. An easy review gives you almost nothing: if the word surfaced instantly, the moment was chosen too early.
Why the intervals grow
Every successful recall strengthens the trace, which means the next encounter can be pushed further out. A word you have confidently recalled several times returns in weeks rather than the next day — freeing your time for whatever is genuinely shaky.
The reverse holds too: a mistake means the interval was too long, so the word comes back much sooner. The schedule keeps adjusting to you rather than to an average.
When a word moves into "Know"
In the progress counters your words are split into "Learning" and "Know". The line runs along the stage: a word enters "Know" once it reaches "Confident". Until then it counts as being learned, even if you are already answering it correctly.
The move usually takes three correct answers in a row — each one on its own due date, not all in one sitting. The gaps between them grow, so what matters is the calendar rather than the number of sessions: a word taken on today needs roughly two weeks to reach "Know", however much you study in between.
A mistake breaks that run and the count starts over. Hence a picture that looks like a stall: you study every day and the "Know" counter sits still. Words ripen in batches and cross the line together — usually a week or two after you started learning them.
What this buys you over time
Your dictionary grows while the daily load barely does: the better you know a word, the more rarely it returns. That is what makes it possible to keep hundreds of words active while spending the usual few minutes a day.