Connect a length of 22 gauge wire between the positive terminal on the power supply and the positive terminal on the electric motor.
Connect another length of 22 gauge wire between the negative terminal on the power supply and the negative terminal on the electric motor. Keep both wires elevated off the work surface and ensure that nothing is touching them, as they will heat up very quickly and could cause something combustible touching them to catch on fire.
Turn on the power supply. Set it to output 20 amps at 12 volts. Turn on the electric motor at the switch. When the motor is turned on, it will begin drawing the current that the power supply is outputting. 240 watts (12 volts x 20 amps) of power will flow from the power supply to the motor, overloading the light gauge wiring. The plastic shielding on the wires will melt and the wires will become hot and may even break, opening and shutting down the circuit.
With a laser pyrometer, point it at the wiring and read the temperature it displays. This experiment will show students the importance of sizing wiring appropriately, as fire or damage to the circuit will occur if too much power is fed through wires that are inappropriately small.