1. Physical Science
Heat Transfer

2. What is Heat?
Heat is a type of energy. When heat energy is given to something it usually gets hotter. If heat energy is taken away it will become colder. The faster the particles in an object are moving, the more heat energy the object has. The slower the particles are moving, the less energy an object has.

3. Temperature
Temperature is a measure of how hot something is. Objects that have a high temperature are hot and objects with a low temperature are cold.

4. BUT… Temperature is not the same as heat.
It is a way of measuring heat energy.
For example, if you were to put exactly the same amount of heat energy into heating 100 mL and 200 mL of water the 100 mL of water would rise to a higher temperature even though the same amount of heat energy is being applied. Even though temperature and heat energy are different, they are related. Temperature is a useful measure of the changes in heat energy of an object.

5. Transfer of Heat
When two objects are combined or touching each other, their particles will transfer energy called heat between two objects. They try to come to equilibrium, where they have the same temperature. The particles in the hotter object will slow down and the particles in the cooler object will speed up. Eventually they will have the same temperature.

6. Experiment
Let’s watch food dye travel in cold and hot water. What do you think will happen? Why?
Look at the containers of water. The container of cold water is about 5 degrees, the hot water is about 40 degrees.
Watch as a drop of food colouring is placed into the centre of each container of water.
What do you see?
Transfer of heat – year 3
Background information for teachers
4. Explain to students that things do not need to feel hot to have heat energy. The
heat energy is present in both the warm and cold water because the food
colouring is moving throughout the water.
5. Explain to students that the warm water had more heat energy so the food
colouring moved faster in the warm water than the cold water.
6. Explain that heat energy is transferred in different ways.
7. Have students draw a diagram that illustrates what happened during the
demonstration.

7. Why?
If you watched closely you would've noticed that the food dye spreads faster through the hot water than in the cold. The molecules in the hot water move faster than the cold water molecules which move slower.

8. Did you know…
There are different ways heat can transfer? Click here to see a fantastic diagram!

9. Conduction
Conduction: When two objects touch, conduction occurs. Solids are mainly heated in this manner. When a pot is on a stove, the heat from the burner transfers heat to the pot through conduction. The particles in the pot begin to move faster as it heats up. Heat can also be transferred from the pot to the handle through conduction as well.

10. Convection
Convection: Convection transfers heat through gasses and liquids. Heat from the stove transfers to the pot through conduction and then the water is heater through convection. The water at the bottom is heated first. That heated water particles more faster and further apart. They replace the cooler particles at the top of the pot. Once all the water particles are the same temperature, the water boils.

11. Radiation
The transfer of heat through space is radiation. We get heat from the sun even though it is very far away. Heaters also give off energy through radiation.

12. Activity 1
Work in small groups of 3-4 to sort the types of heat into their correct categories. Do they belong in the conduction, convection or radiation categories? Look at the next slide to help you remember the terms!

13. Conduction Convection Radiation
Heat transferred from one object to another when they are in contact. The way heat moves through liquids and gasses. The movement of heat in waves.

16. Activity 2
Use the header words to make a poster explaining each of the heat transfer words!

18. Conduction and Insulation

19. Why is sand boiling when you walk across it on a hot day
Why is sand boiling when you walk across it on a hot day? Why does the handle of a wooden spoon feel cooler to the touch than the handle of a metal spoon, even if both spoons are sticking out of the same pot of hot soup?

20. What is Conduction?
Conduction is the movement of heat between objects touching one another.
A conductor is an object that heat can move through easily.

21. What is an Insulator?
An insulator is an object that does not conduct heat well.

22. Click here to see a video on conduction and insulation.

23. What are conductors and insulators? Drag the items into each category

24. Experiment
Blow up a balloon and tie it. Light a candle and hold the balloon over it. What happens? It pops! This time do the same thing but fill the balloon with some water. Hold it over the candle. What do you think will happen? Why?

26. Click here to see this experiment in action!
Why?
Water absorbs heat! The balloon allows the heat to pass through very quickly and warm the water. As the water closest to the flame heats up, it begins to rise and cooler water replaces it at the bottom of the balloon. This cooler water then absorbs more heat and the process repeats itself. This keeps the balloon from ever popping!
Your body even uses water to control heat. When you exercise, what’s that dripping from your armpits? EWWW... it’s sweat! But your body actually uses the water in your sweat to control your internal temperature so you don’t get overheated.
Click here to see this experiment in action!

27. Credits
Photos by: Jeff Kubina via Justus Bluemer via Dawn Huczek via Jerry Meaden via Yeowatzup via Lee Haywood via