Explanations you can move
Short explanations of ideas that students trip over, each with one figure you can drag until it makes sense. Free, without an account.
- What a derivative isCalculusThe slope of a curve at one point, found by letting a secant shrink.
- What an integral adds upCalculusThe area under a curve as a sum of thin rectangles.
- Sine and cosine on the unit circleTrigonometryThe two coordinates of one point going round a circle.
- The dot productLinear algebraOne number that says how much two vectors point the same way.
- What a matrix doesLinear algebraA 2×2 matrix moves every point of the plane; its columns say where.
- Why averages are bell-shapedStatisticsAverage enough random values and the bell curve appears, whatever you started from.
- Why a thrown ball follows a parabolaPhysicsTwo simple motions at once: steady sideways, accelerating downward.
- Why exponential growth surprisesGrowthGrowing by a share instead of an amount, and what stops it.