Open mathematics courseware
Mathematics, built idea by idea.
Free, rigorous video courses. Every chapter opens with a question worth asking — and closes with the tools to answer it.
28
Units
133
Chapters
10–16
Min per lesson
$0
Free forever
The catalog
All courses →Course I
7 units · 27 chapters
AP Physics 2: Algebra-Based
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Course II
7 units · 42 chapters
AMC 10: From Problem 1 to the AIME
From five answer choices that give one away to the problems that decide an AIME ticket — algebra, counting, probability, number theory and geometry, each taught by the idea that opens the problem.
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Course III
6 units · 18 chapters
AP Physics 1: Algebra-Based
From a minus sign that does the work of an arrow to a yo-yo that loses the race by spinning — motion, force, energy, momentum and rotation, told as one connected story.
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Course IV
8 units · 46 chapters
AP Calculus AB
From the paradox of instant speed to volumes of revolution — the complete AB curriculum, told as one connected story.
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In preparation
AP Calculus BC
Winter 2026
In preparation
Linear Algebra
Spring 2027
Free lesson · Unit 3, Chapter 14
The Chain Rule
“Most functions in the wild are nested. Rates multiply through a chain — like gears passing rotation along.”
Watch the lesson — 11 min