Do you know what a child can learn from putting a crisp packet in the microwave?
It sounds shocking and is exactly that.
A crisp packet is made with an outer layer of plastic and an inner layer of metal. If put in a microwave (for no more than 3 - 4 seconds) the plastic shrinks around the metal and causes cracks in it. The electrical current induced by the microwave builds up and can overcome the resistance of the air and jump from one side of the crack to the other.
The experiment apart from being a fun firework display shows how electromagnet waves such as microwaves can induce an electrical current in metal conductors.
This is how radio waves, televisions and telephone signals are transmitted and received and is why you should never use a mobile phone on a petrol station forecourt.
Try using an old CD next, what happens?
Below is a link to a brilliant web site with fantastic experiments to do using house hold items that can keep the children absorbed for hours.