Home / Guides / How to remember vocabulary

How to remember vocabulary in a new language

Last updated July 7, 2026 · 7 min read

Why you forget words (the forgetting curve)

In the 1880s, the German psychologist Hermann Ebbinghaus ran memory experiments on himself and mapped how quickly new information disappears. The result, now known as the forgetting curve, shows a sharp early drop — a lot of what you learn is gone within a day or two — followed by a slower decline. This isn't a flaw in how you personally learn. It's the default behavior of memory for anyone, for anything new. A vocabulary word you hear once and never touch again is, by default, on that same curve.

The forgetting curve isn't a life sentence, though. Every time you successfully recall something before you fully lose it, the curve resets and flattens — the next drop-off is slower than the last. That's the entire mechanism behind spaced repetition.

Spaced repetition: reviewing at the right time

The mistake most learners make isn't reviewing too little — it's reviewing at the wrong time. Reviewing a word you already know cold, every single day, wastes a session on something you didn't need to practice. Waiting three months to review a shaky word means you've already lost it, and you're relearning it from scratch instead of reinforcing it. The useful window is narrower: review a word again right around when you're about to forget it, not well before and not well after.

A common rule of thumb in spaced-repetition research is to space each review at roughly 10–20% of how long you actually want to remember something for. Want to know a word in a month? Review it every few days at first, then stretch the gap as it holds. Doing that by hand for hundreds of words is impractical, which is why CatchFrase's smart review runs on FSRS — an algorithm that tracks how you've done with each specific word and schedules the next review right before your personal forgetting point, instead of on a fixed daily list.

Active recall beats re-reading

Rereading a word list feels productive because the words look familiar by the third pass — but familiarity isn't memory. Research consistently shows that forcing yourself to retrieve a word from memory, without looking at the answer first, builds a stronger and more durable memory trace than simply re-exposing yourself to it. This is why flipping a flashcard and trying to answer before you look works better than just reading both sides in sequence. CatchFrase's review is built around this: you're asked to produce the word, not just glance past it again.

Saying it out loud beats recognizing it

There's a real difference between recognizing a word in a multiple-choice list and producing it yourself, unprompted, out loud. Recognition is the easiest, weakest form of memory — it's why a word can look familiar on a quiz and still not come to you in conversation. Speaking a word or phrase out loud closes that gap, because it's closer to how you'll actually need to use it. CatchFrase leans on this directly: say the word or the full phrase out loud, and it shows your words back to you live as you speak, so you know whether you actually said it — not just whether you recognized it.

Personal context makes it stick

Words tied to your own life are easier to hold onto than words studied in isolation. A cup becomes la taza in Spanish or コップ (koppu) in Japanese much more easily when it's the cup on your actual desk than when it's line 12 of a downloaded word list. Every time you use the real object, you get a small, free review you didn't have to schedule. This is the idea behind catching vocabulary from photos of things around you instead of memorizing a generic list.

Common questions

What is the forgetting curve?

The forgetting curve comes from Hermann Ebbinghaus's 19th-century memory research. It shows that a newly learned piece of information fades fastest in the first hours and days after you learn it, then levels off. It's why a word you learned yesterday can feel gone today, even though you were sure you had it.

How often should I review a new word?

Less often than you'd think, but not so rarely that you forget it completely. A common rule of thumb in spaced-repetition research is to space each review at roughly 10-20% of how long you want to remember the word for — reviewing more often early on and stretching the gap out as the word sticks. CatchFrase's smart review calculates this per word for you.

Does CatchFrase use spaced repetition?

Yes. CatchFrase's smart review runs on FSRS, an algorithm that estimates when you're likely to forget a specific word based on how you've done with it before, and schedules your next review right before that point.