Wire up components on the circuit board below, then click Run — your code controls the board for real.
Drag a component's body to move it. Click a pin, then click a component lead (or the other way round) to wire them — the wire color below applies to the next wire you draw. Click a wire to remove it. Double-click an LED to cycle its color, or a resistor to cycle its value. While a program is running, drag a sensor's slider, click an IR sensor to simulate an obstacle, or hold a button's body to press it.