Try the teeth test

You’ll need

5-8 clean jam jars
5-8 eggs
A selection of fizzy drinks
Vinegar
Coffee
Toothpaste
Water

Egg-cellent preparation

Get some clean jam jars with lids, and the same number of eggs
Prepare all of the different liquids. You’ll need water, vinegar, coffee and a selection of fizzy drinks. Try to get a mixture of different colours to make the experiment more interesting. You could even try some ‘diet’ or ‘light’ soft drinks to see if they affect the eggs differently
Prepare the coffee without any milk, and allow it to cool down.

Talk about teeth

Explain that the experiment will show the effects of certain drinks on our teeth, but because we can’t use real teeth, we’re using eggs.
This is because drinks affect eggshells similarly to how our they affect our teeth.
Ask everyone how they take care of their teeth. How often do they brush? How long do they brush for? Do they floss? Do they use mouthwash? Do they use straws when drinking acidic drinks?

Egg-citing experiment

This experiment should be done over two meetings to allow the liquids to interact with the eggs
The clean, empty jam jars should be half-filled with each of the liquids. You should do three jars with coffee in – two regular and one with some sugar in.
Cover one egg in toothpaste. This one will go in one of the regular coffee jars to see whether toothpaste changes how the coffee affects the egg.
Place an egg in each of the jars and screw the lid on. Be sure to label what is in each of the jars.
Leave the eggs in the liquids for a week until your next meet to give the liquids a chance to affect the eggs.

Eggs-amination time

After a week, the person leading the activity should ask everyone what they think has happened to each of the eggs.

Which mixture will have stained the eggs the most? What changes do they think will have happened to the eggs?

Remove the eggs from the jars one by one, and look at how the liquids have affected each of the eggs. Some will appear discoloured or stained by the liquid.
The egg in vinegar should be rinsed with water, and if it is gently rubbed, the shell should come away. This is because the vinegar is very acidic and decays the eggshell. The person leading the activity should explain that this is an extreme example, but that soft drinks also contain a lot of acid, and so drinking lots of them can be damaging to your teeth.
Compare the eggs that had been left in coffee to see whether the one in toothpaste was affected less than the others. It should be less stained than the eggs without toothpaste.

Reflection

This activity helped you think about the effect of drinks on your teeth. What surprised you most about the experiment? How has this helped you think about looking after your teeth? What do you think would happen to your teeth under the same conditions? (The experiment shows that sugary and acidic drinks are damaging to your teeth if you drink them too often. The egg covered in toothpaste should have also shown that it helps prevent damage to teeth, so it is really important to look after your teeth by regularly brushing them).

This activity was also about problem-solving. We all made predictions about what we thought might happen in the experiments. What led you to make those predictions? What did you learn from the ones that did and didn’t come true?

Safety

All activities must be safely managed. You must complete a thorough risk assessment and take appropriate steps to reduce risk. Use the safety checklist to help you plan and risk assess your activity. Always get approval for the activity, and have suitable supervision and an InTouch process.

Science: Supervise young people, and only do science activities that are advised and age appropriate for your section. Test activities first, to make sure you’re confident you can lead them safely. Use protective clothing where necessary.
Food: Remember to check for allergies, eating problems, fasting or dietary requirements and adjust the recipe as needed. Make sure you’ve suitable areas for storing and preparing food and avoid cross contamination of different foods. Take a look at our guidance on food safety and hygiene.
Water games and activities: Be careful when doing activities with, in, or near water. Check surfaces and reduce the risk of slipping where possible. Make sure you have appropriate supervision for this activity.