Watch a 3-D animation of a model cell crawling.

Discover the meaning of evolutionary fitness in this predator/prey simulation.

Daily cycles of the city are projected onto a miniature topographic map of San Francisco.

Two cylinders that look the same may roll downhill at different rates.

Construct a simple hydrometer to compare the densities of solutions.

“g,” that’s interesting! Investigating gravity.

Model the carbon cycle and its principal reservoirs and flow rates using rice.

Light gets dimmer the farther it travels–and a bit of simple math explains how.

Why the world gets dark so fast outside the circle of the campfire.

Explainers do biology and botany demonstrations.

Movement is reduced to stillness, given an astronomical gear ratio.