Dim the light

Ask while they play

What happened to the light when you turned the knob back? How is the pencil-lead strip like the materials you tested?

Spot it at home

• Dimmer switches, volume knobs, fan speed dials, and a tap that lets more or less water through.

What other knobs at home change 'how much'?

Talk about it later

How is a tap like a dimmer?