Keeping Drinks Hot

What you'll need:

4 cups that are exactly the same
Hot water
Cold water
Cold milk
A thermometer
Spoons


Instructions:

Half fill each cup with hot water.
Check that all of the cups are at the same temperature. Leave the thermometer in one of the cups for now.
Add 1 spoon of milk to the first cup. Add 1 spoon of cold water to the second cup. Add 3 spoons of milk to the third cup. Don't add anything to the last cup.
Check the temperature of each cup every minute with the thermometer. Which cup of water stays hot for the longest.


What's happening?

This one's up to you, do you think you can you explain it?

Some other interesting questions related to this topic include:

What are some good ways of keeping drinks hot?
Have you heard of the word ‘insulation’?
What happens if you want to keep a drink cool rather than hot?
Which is more likely to keep a drink hot for longer: a tall thin cup or a wide shallow cup?
Do some liquids cool faster than others?
What type of cup is better for keeping drinks hot: paper, plastic, clay or glass?