Story 9. Brush Twice a Day (II)
We boil the egg.
When it has cooled, Mom hits the shell with a spoon.
The shell doesn't break.
It protects the inside of the egg.
She says, Your teeth have a shell, too.
It is called enamel.
Now, the fun part.
We fill the jar with vinegar.
Then, we put the egg inside and close the jar with a lid.
Now, we wait.
What will happen?
It is exciting.
Two days later, we open the jar.
The eggshell has become really soft.
It is breaking into small pieces.
Wow!
What is that about?
The vinegar is a strong acid, just like many foods we eat, Mom says.
The vinegar softens the eggshell so it cannot protect what is inside anymore.
Mom smiles at me and says, That is why you must brush your teeth.
Brushing cleans the acid off from them.
If you do not brush, the acid will break the enamel.
You will have many cavities and toothaches after.
