How the series is ordered

Why the videos are numbered, and why review videos keep coming back

Each series is published one video a day, in order. The order is not arbitrary: it is generated from a spaced-repetition schedule, the same idea behind the Ebbinghaus forgetting curve. A word is reviewed just before it would normally be forgotten, so each repetition costs little and buys a lot.

The intervals

After a word is first taught, it comes back on day 1, day 3, day 7 and day 15 after the previous time it was seen. Words that fall due on the same day are packed into a single review video, up to four per video, so that the feed never turns into nothing but review.

What that produces

For 89 words, the schedule works out to 201 videos: 89 teaching videos and 112 review videos. Both series are built the same way and run to the same length.

Two kinds of video

• A new word. The word is shown in syllable chunks with its pronunciation, then a short animation tied to the word's meaning, then the meaning itself, then a sentence that puts it in context. Everything is read aloud, and the timing follows the real length of the narration.
• A review. The animation plays first with the word hidden, so there is a moment of trying to remember before the answer appears. Recall is what makes the repetition stick.

Finding a word again

Every video carries its episode number in the first frame, which is also the cover shown in the feed. The word lists on this site give the episode number for each word: elementary and TOEIC.