1. Animals including Humans
Year 4
Lesson 5
LI: To carry out a fair test.

2. Input Why is it important to keep your teeth healthy?
How do you keep our teeth healthy?
Remind children about the previous lesson about how to look after our teeth and why it is important.
Brushing your teeth twice a day for 2 minutes helps get fid of plaque which is a bacteria that coats the teeth. Plaque contributes to gum disease and tooth decay.

3. Tooth structure Show a picture of the structure of a tooth.
The enamel protects the tooth from the wear and tear of chewing.
The dentin supports the enamel of the tooth.
The pulp in the centre of the tooth which is a soft tissue that contains blood, lymph vessels and nerves.
Cementum covers the root of the tooth and helps attach the tooth to the bone in your jaw.

4. Tooth structure The tooth is like an egg:
The shell is like the enamel- protecting the insides of the egg.
The white of the egg represents the dentin
The yolk signifies the pulp.
Show a picture of the structure of a tooth and link this with an egg.

5. Experiment
We are going to be carrying out an experiment that tests how acid in drinks can damage our teeth and what toothpaste does to protect our teeth.
Explain that they are going to be carrying out an experiment to show us how acid in things we drink can damage our teeth. The experiment will also show the children how protective tooth paste is for our teeth.

6. Experiment
We are going to put a hardboiled egg into different drinks (water, Coca Cola, orange juice, milk, blackcurrant squash).
Each group will get 1 liquid each to test.
Put another egg (this time covered in toothpaste) into another beaker with the same liquid in.
The liquids will be left for a week (in a fridge).
Explain that they are going to be carrying out an experiment to show us how acid in things we drink can damage our teeth. The experiment will also show the children how protective tooth paste is for our teeth.

7. Fair test
What does this mean? How can we make our experiment fair? Why is it important to make our test fair?
Discuss what it means to carry out a fair test.

8. Make sure you keep everything the same!
Activity
Set up the experiment
Make sure you keep everything the same!
Children to set up experiment.
Each group will have 2 jugs, 2 eggs and a different liquid to put their egg in- remembering all groups must have the same amount of liquid to make it fair.
One egg will be left untouched in the liquid; the other egg will be coated in toothpaste.
The experiment should be left in the fridge for a week.

9. Plenary
What does the experiment show? What has happened to the eggs? What does this tell us about brushing our teeth?
After a week the children should look back at the experiment.
Link the conclusion of the experiment back to the importance of keeping our teeth healthy.