The Soda and Egg Brushing Experiment

I recently ran across an experiment in a blog that I immediately knew I was going to let Mr. BANG and Drama Queen carry out.  The idea of it was that, since eggshells and tooth enamel are similar, you can use boiled eggs to show the effect of thoroughly brushing your teeth!

The process starts with boiling eggs ahead of time.  Each child will need one egg and you’ll probably want one to demonstrate.  It is important that the eggs not be cracked, so you may want to boil a few extras as well.

The next step is to let the eggs soak in Coke for 5 or more hours.  I let the children place the eggs in a bowl and pour the Coke in.  I probably used too wide of a container (or just didn’t have enough Coke), because the Coke didn’t fully cover the eggs.

   

Around 6 hours later, I had the children sit at the table with toothbrushes ready.  I talked about the similarities between tooth enamel and eggshells, and compared the stains from the Coke with plaque that forms on their teeth.  I passed around a mirror so we could all look at our teeth (which had been brushed not long before).

I also showed two eggs – one soaked and one not soaked – side by side for comparison.

I then began my demonstration of brushing the egg.  They were amazed to see more and more of the Coke stain get brushed away.  I did just a small section, then handed out eggs, toothbrushes, and dabs of toothpaste to them.

They excitedly got to work.  Drama Queen was able to immediately focus on one area and start making a significant difference on the stain of her egg.  Mr. BANG was moving his toothbrush haphazardly around the egg, so I guided him to just brush one area at a time.  Once he got that down, he really started to see the difference.  They brushed and brushed and brushed.

  

     

Along the way, Drama Queen asked for a bowl of water to rinse her toothbrush in, which turned out to be an excellent suggestion.  Otherwise, she was largely just pushing the ugly brown mess around the egg, covering the sections she had already brushed white.  One thing I would do differently next time is actually have a blob of toothpaste in their bowls, so they could get more as desired.

By the time they finished, Drama Queen’s egg looked just about as white as our egg that had not been soaked in Coke, and even Mr. BANG’s was pretty close to it.

The top egg is the un-soaked one, and the bottom one shows the un-brushed side of my demonstration egg. 

The egg on the left is Drama Queen’s final product, and the one on the right is Mr. BANG’s brushed egg.

 

Drama Queen then finished brushing my demo egg, just because she wanted to keep brushing.  🙂

We ended the experiment with a discussion on what we learned about brushing, such as how long it took to get the eggs white again (some difference was made right away, but it took a few minutes of brushing to get them fully white again).  We were then able to refer back to the experiment when it was time to brush teeth again.