Climb from pushes and pulls to the physics of the stars

How the Physics Ladder works

1. Find your rung. A short check, at most 30 questions, skips what you already know and finds your starting point.
2. Learn from first principles. Each topic is one small idea. The lesson shows why it works, then walks through worked examples one step at a time.
3. Master it before moving on. Three right answers, the last two in a row, pass a topic. If a topic gets hard, we point you to the skill underneath it.
4. Review, spaced out. Passed topics come back after 1 day, then 3, 7, 16 days and longer, for two quick problems each. Harder topics that use an older one count as practice for it.
5. Mix it up. Reviews and checkpoint quizzes mix problems from different topics, so you learn to tell which method a problem needs.
6. Earn XP. About one point per minute of focused work. Set a daily goal and keep your streak going.
7. One climb across subjects. Every ladder shares your XP, streak and reviews. When a topic needs a skill from another ladder, such as the algebra behind a formula, that skill comes first, labeled with its ladder.

Why these steps: the U.S. Institute of Education Sciences practice guide Organizing Instruction and Study to Improve Student Learning (Pashler and others, NCER 2007-2004) recommends spacing reviews out over time, alternating worked examples with problems students solve on their own, pairing pictures with words, and using quizzes to bring key content back. The Physics Ladder is built around those ideas.