39 seconds · real product run

It finds the sign error, thenshows where it happened.

Jim Hefferon's Linear Algebra becomes a course, a linear-systems problem, written work, specific feedback, and scheduled recall.

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  1. Start with a book you keep bouncing off.
  2. It reads the whole book and builds your course.
  3. Not a summary of it. Chapters out of the source.
  4. Then it sets you a problem from the chapter you just read.
  5. And it reads what you actually wrote.
  6. It found the one clause that was wrong. And it says why.
  7. Then it brings it back at one, three, and seven days.
  8. 1,500 free credits. One-time packs. No subscription.
Try a problem from your book

Every recording is a real product run on a real book — no mockups, no edited answers. Each one shows the same loop on a different subject: the book becomes a course, the course sets a problem, and the feedback names what specifically went wrong.

Prefer reading first? We wrote up how to self-study linear algebra when there is no answer key, and the Study Junkie blog covers the rest of the method — remembering what you read, scheduled recall, and turning sources into courses.