Learn a whole textbook, one unit at a time.
Pick a course built from an open textbook and study it as short verified units, with a review schedule that makes it stick.
Every claim checked against the source textbook
1Pick a course
Browse full textbooks already built into courses. Add one and it's yours to study.
2Study in short units
Every concept gets its own unit, written from the passage it belongs to and checked against it.
3Keep what you learn
Reviews come back right before you'd forget, so it sticks.
See it, don't just read about it
A real question from a real course. Give it a try.
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Built from open textbooks
Every course is built from an openly licensed or public domain textbook, and each one credits the work it came from. Real books by academics, not content invented by a model.
How a course gets made →