This week, Year 4 have begun to investigate the effects of acid on our teeth.
Sugar creates a sticky substance, called plaque, which can build on your teeth and become a home for bacteria. And guess what that bacteria does? It produces acids which act directly on your teeth, slowly eating them away.
What is tooth decay?
Bacteria in the mouth feed on sugars from foods and drinks. These bacteria produce acid, which damages the outer surface of the tooth (the enamel). Saliva helps to repair this damage, but if over time there is more damage than repair, it leaves a cavity or ‘hole’ in the tooth.
To begin with, we discussed what it was we wanted to find out. The children were able to generate some scientific questions. This project focuses on two different dental hygiene issues: stains and decay.
What equipment will we need?
I wonder if we should use different liquids?
How will we know that the shell has been damaged?
Teeth are made from minerals. These minerals will begin to dissolve if exposed to acid. We decided to use hard boiled eggs as a substitute for teeth. This may seem like an unlikely pairing for an experiment, but eggshells make a realistic model of dental enamel.
Next, we chose a scientific enquiry to help us to answer our questions.
Let’s put the eggs into the liquids and look at them at the end of the day.
“I wonder if we will see any changes straight away?
Maybe we should leave them for a week.”
We could observe the eggs every few days and record any changes.
The class decided that an ‘observation over time‘ would be the best way to get some information about tooth decay in a very visual way.
Make it a fair test
To make this a fair test, the children recorded what needed to stay the same and what could change.
Then, it was time to make some predictions.
What do you think will happen to each egg? Why?
I think the egg in the water won’t look any different.
The coke will stain the egg.
The shell will disintegrate in the vinegar.
I predict that the sugar free juice will weaken the eggshell.
The outside will become sticky and change colour
Five eggs have been placed in different liquids: coke, vinegar, low sugar juice, water and milk. The children will observe and record any changes every couple of days. 
Stay posted to find out our results.