The switch is like a gate to a field. When you open the gate, the little electrons runs through the gate fast up the copper wire path to the device, then they run back down again. Its like letting sheep out of the field, except the sheep tend not to come back again.
to buildersmate.
the electrons in a wire actually only move quite slowly (typically of the order of a few millimetres per second), but the overall effect of the current travels extremely quickly
If you imagine the wire is a long hollow tube and the electrons are marbles in a line within that tube, when you push a marble in one end, a marble will drop out the other end. So even though electricty moves really slow, it's overall impression is that it is extremely fast.