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Understanding the World 30 March 2020

An experiment to try - if you are able to and wish to do so! If you do complete the experiment, we would love to see pictures and hear what your child said about the experience (this could be via 2Simple or pictures/drawings and written into their home learning book).

How is an Egg Shell Like Your Teeth?

Question: How do cola and toothpaste affect eggs?


  • 250 ml (1 cup) cola drinking glass or open jar
  • white shelled egg
  • old toothbrush
  • fluoride toothpaste
  • clock or timer


  1. Place an egg in a glass or jar filled with cola, taking note of its colour.  
  2. Leave the egg for 30 - 60 minutes.
  3.  Remove the egg and notice the brown colour which covers the egg.
  4. Use a toothbrush and toothpaste to brush the egg back to its original colour.

Explanation: Sugar (in the cola) combines with bacteria in your mouth to form acid. This acid, along with the extra acid (in the cola as well), attacks the teeth. Over time, these acid attacks weaken tooth enamel, the hard outer covering of your teeth, causing discolouration of your teeth as well as holes in your teeth (cavities). The fluoride treatment (your toothpaste) protects the egg's shell from the acid. Your teeth need to be protected from the acids in your mouth with fluoride too.