A bit of a magic trick you can do, using science concepts to help you find the answer.
What you need:
- 3x 20 cent coins, made in different years
What to do:
- Call for an assistant to help you with your magic trick. Ask the assistant to choose a coin, and look at the year printed on it, but not to tell you.
- Ask everyone around to have a look at the coin to see what year it was printed.
- Bring the coin back to you and put it down with the other coins.
- Have your assistant mix the coins up.
- Feel each coin. One should feel hotter. This is the coin that was chosen.
- Choose the hot coin and read the year off it, amazing your audience.
What happens:
Metal is a good conductor. When people hold the coin, it absorbs the heat and feels warm. The coins that aren’t held stay cold – it is important that the other coins aren’t handled too much or they will heat up and you won’t be able to tell the difference. To help you, once the coin is handed back, you can hold it tightly, helping it to get warm, before your assistant jumbles them all up.