Most parents have had to deal with at least a few complaints of, “Ah, do I have to brush my teeth?” This hands-on science project is a great way to give kids a very visual answer to that question and teach kids about the basics of dental health.

Your teeth are protected by enamel but the foods that you eat can damage that enamel if you don’t brush well. The concept behind this project is simple — egg shells are very similar to tooth enamel so we set boiled eggs in different solutions over night to see how they would react. My kids were a bit disgusted by the results and we’ve had very dedicated teeth brushers every since.

Supplies

• 2 hard boiled eggs
• 2 glass jars
• A packet of Kool-Aid
• Vinegar

Instructions

Hard boil 3 eggs and let them cool completely. We boiled an extra egg just so my kids could compare the changes they saw on the other eggs.

Fill one of your glass jars with water, one with vinegar (we just used distilled white vinegar), and one with Kool-Aid. If you don’t have any Kool-Aid, you can substitute any sugary drink. We didn’t have any on hand because personally I don’t think any sort of food coloring is edible, but we found a generic packet for something like $0.15.

Have kids observe what each egg looks like before adding it to any of the solutions. This is a great time to talk about what a hypothesis is if you have older kids. We’re currently obsessed with Brain Pop videos and they have a great one on the scientific method. (On a side-not, I’m not associated with Brain Pop in any way. It’s just something we use on a regular basis in our homeschool curriculum and I highly recommend it.)

Add a hard boiled egg to each jar and leave them overnight.

Let the eggs sit for at least 24 hours and then pull them out of the jars so you can observe any changes. The egg in the water will look identical to the way it started out. Explain to your kids that this is what happens when we brush our teeth well.

Pull out the egg from the vinegar solution. Explain to your kids that some foods have higher acid content like citrus and tomato sauce. Even though these foods are good for us, they need to be cleaned off our teeth. The egg in the vinegar was the most interesting to us because the shell became soft.

Remove the egg from the Kool-Aid. Explain to your kids that this is what happens when sugary foods sit on your teeth for too long. The egg will have a rough surface because the sugar will have eaten away at the shell.

You can expand this project by having younger kids draw pictures of the each egg, before and after they sat in the solutions over night. Older kids can write a hypothesis of what they think will happen and write their conclusion the next day.

Follow-up this project with some great books on dental health. Here are a few of our favorites:

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