CritABCD
IB DP Physics · SL and HL · Free

Learn physics by doing

Short lessons you can do alone: read one idea, predict, test it in a simulation, then check yourself. Built class by class from our own classroom notes.

Welcome to Physics · Class 1 · Intro to Physics

0 Preface to the syllabus

Before any equation: what physics studies, what "measurable" means, the units everything is built from, what makes things move, and the map of the whole course.

Theme A · Space, time and motion · Class 2 · 1D Motion

A.1 Kinematics: describing motion

Start with the best question you can ask about motion, see how repetition gave us clocks, meet an ancient paradox, and model motion yourself.