Interactive exploration
Cities & TransportTraffic jams and traffic waves
Why do traffic jams happen?
One driver brakes. A slowdown travels through the road. Find out how a small action can affect everyone behind it.
Small actions. Surprising effects.
Brake a car. Turn a gear. Squeeze a lever. Trace an action through connected parts.
Start with the first experiment Search & filter this collection 3 available explorations · choose any starting point
Interactive exploration
Machines & MotionGears and gear ratios
How do gears trade speed for turning force?
Turn once. Count what happens. Discover gear ratios, real-world uses, and why different jobs need different gears.
Interactive exploration
Machines & MotionHydraulic brakes
How does a little lever stop a spinning wheel?
Squeeze a hydraulic brake. See inside the caliper, change piston sizes, and discover how pressure becomes force.
Take these steps at your own pace. Your place is not saved as account progress or scored.