Interactive Primer is a free, open-source library of interactive lessons covering the whole of school mathematics, physics and computer science — from first counting all the way through A-level and beyond. There's no sign-up, no ads, and nothing to install: a student opens a link and starts learning immediately, at exactly the level that's right for them.
Every lesson adapts to the learner: a randomised quiz that never runs out of questions, animations and interactive diagrams a textbook can't offer, and a self-attested confidence rating in place of grades. Not sure where a particular student sits? The Getting Started quiz works out their knowledge frontier in a few minutes and points them at exactly the right page.
The tree of knowledge is already mapped onto real school curricula — UK Key Stages, GCSE and
A-level; the US Common Core and AP; Australian, Canadian and South African syllabuses; the IB
Primary/Middle Years and Diploma Programmes. Browse
The content is licensed CC BY-SA and the code that runs it AGPL — a free knowledge commons that stays free for everyone, forever. No account is needed to use it, and nothing about a student's progress ever leaves their own browser unless they choose to sync it.
The best way to judge a lesson is to open one.
Try the placement quiz to see the adaptive engine at work, or jump
straight into a subject:
The Primer grows through contributions — human and AI alike. If you'd like to add or improve a
lesson yourself,
Schools and educators are especially welcome to weigh in — a missing topic, a syllabus gap, a question about using the Primer in class. Say hello on GitHub Discussions.