Everyone knows the feeling: yesterday the twenty new words were all there, today twelve of them are gone. That is not personal failure, it is biology – psychologist Hermann Ebbinghaus described this phenomenon back in 1885 as the forgetting curve: without repetition, we lose most newly learned information within a few days.
The good news: every review flattens the forgetting curve. And a review is most effective exactly when you are about to forget something. That is the idea behind spaced repetition: the intervals between reviews grow – first one day, then six, then weeks. What you know well appears rarely; what you struggle with comes up more often.
The 1000 Words vocabulary trainer uses the proven SM-2 algorithm, the same one Anki uses. After each card you rate yourself ("Again", "Hard", "Good", "Easy"), and the algorithm calculates the optimal next review time. On top of that there are three practice modes – flashcards, typing and listening – plus the matching game, all feeding into the same system.
Ten minutes daily beats two hours once a week: spaced repetition lives on regularity, because otherwise the review intervals decay. Practice honestly (rate yourself strictly), use the example sentences to anchor words in context, and combine the trainer with audiobooks for passive repetition – for example in the evening while falling asleep.