Each lesson is one A-Level idea you can play with in the browser, built to make it click before the formulas. Free to use.
Chemical Equilibria
Le Chatelier · ICE tables · Kp vs Kc
Start with a reaction that is not at equilibrium. Add reactants, remove products, change pressure, and watch the system respond in real time. Track Q and K as they converge.
Integration by Parts
Geometric proof · LIATE · cyclic integrals
Start from the product rule, not the formula. Drag a point on the curve and watch two areas always sum to the same rectangle. The formula stops looking arbitrary.
Complex Numbers
Argand plane · polar form · De Moivre
Rotate vectors on the Argand plane, see multiplication as rotation, and prove De Moivre’s theorem visually.