How Engrain teaches

Reading something twice feels like learning. It mostly isn't. The methods with the strongest evidence are less comfortable: trying to recall an answer before you see it, and coming back to it after a gap, just before you would forget. Engrain is built around those two.

The five steps

1. Learn. One idea, under 250 words, with one picture or one step-by-step trace. Every code example is run in our tests before it is published, and the output you see is the real output.
2. Predict. You answer a question before the explanation. Being wrong here is useful: the correction sticks better than a fact you only read.
3. Interview angle. The answer you would say out loud in about 30 seconds, the follow-up questions you are likely to get, and the answer that makes interviewers worry.
4. Practice. Code with real tests, running in a sealed sandbox in your browser. Some exercises are timed like the real round.
5. Remember. Three to five flashcards, one fact each.

Reviews

Cards you add come back on a schedule worked out by FSRS, an open-source scheduler that estimates when you are about to forget each card. Say how well you remembered it, and the next gap grows or shrinks. A few minutes a day is enough to keep hundreds of concepts.

Depth when you need it

Below every concept is a ladder of four layers: the core idea, the mechanism underneath, edge cases, and production practice. A first job needs the first layer; senior and staff rounds go further down.

Gates

Each module ends with a gate that checks five skills — recall, explain, apply, debug and design. A path only says you are ready to apply after a full mock loop scored "hire".