Keeping heat in

Equipment:

• hot water
• ice
• salt
• a thermometer
• a thermos
• tin cans
• cotton wool, a sponge, or fleecy material
• a newspaper
• knitted wool

Method:

With your class, make up an effective test for finding the best way to insulate a can of hot water, or a can of salty iced water. (Salt lowers the temperature of melting ice).

Discuss the principles of fair testing, so they are quite sure that their method of testing will give valid results

• Find out which material keeps a can full of iced water cold for longest.
  
• Find out which material keeps a can full of hot water hot for longest.
  
• How did you make sure that the investigations were fair tests?
  
• Does the same material work best for keeping things both hot and cold?