Keep Away Tooth Decay

Children will perform an experiment relating to tooth decay.


Lesson Objective

Children will learn about their teeth and good dental care, and they will perform an experiment about tooth decay.


What You'll Need

  • 6”–8” child-safe mirrors – 1 per child
  • Hard-boiled eggs – 1 per child
  • Cola – 1 cup per child
  • 12 ounce clear cups – 2 per child
  • Toothbrushes – 1 per child
  • Toothpaste – 1 tube
  • Water

What To Do

Note: This experiment will take 2 days to complete.

  1. Distribute mirrors to the children and have them examine their teeth.
  2. Discuss information about their teeth with the children (see Did You Know?).
  3. Display the hard-boiled eggs and compare them to teeth, explaining the shell on the eggs is white like teeth. Tell the children that they will be using eggs to perform an experiment.
  4. Have the children help you carefully place each egg in a cup and completely cover the eggs with the cola.
  5. Ask the children to make predictions about what might happen to the eggs (see Lesson Tips).
  6. The next day, remove the eggs from the liquid and discuss what happened (see Guiding Student Inquiry).
  7. Explain to the children that the cola stained the egg and this is like the way food can stain our teeth.
  8. Distribute a cup filled with water to each child and have them submerge the egg in the water. Explain that the water cannot remove the stain by itself.
  9. Distribute toothbrushes with toothpaste and direct the children to gently brush the egg to remove the stains.
  10. Discuss what might happen to our teeth if we were not to brush them. Explain that the stain on the egg is like the way our teeth can get decayed if we don’t take care of them.

Guiding Student Inquiry

  • Tell me about your teeth.
  • Count your teeth; how many do you have?
  • What do you think might happen to the egg?
  • Describe the egg before and after adding the cola.
  • Explain what you did to remove the stain.
  • What do you think might happen if we were not to brush the egg?
  • Explain what you think might happen to our teeth if we were not to brush them.

Explore, Extend & Integrate

  • This experiment can be extended by placing the eggs in different liquids, such as vinegar, milk, lemon juice, and water. Compare and contrast the results.
  • Arrange to have a dentist or dental hygienist come to visit your classroom.
  • Place the mirrors in the science center to allow for further exploration.
  • Provide a white shirt (to use as a dentist’s lab coat), mirror, and clipboard in the dramatic play area for the children to pretend being a dentist. You can provide toothbrushes for the children to use with the dolls.
  • Provide toothbrushes in the art area to use for painting.

Check for Children’s Understanding

  • Could children describe their teeth?
  • Could children describe what happened to the egg?
  • Could children explain what might happen to our teeth if we were not to brush?


Did You Know?

Our teeth are an important part of our bodies. Our teeth bite and chew our food so it is small enough to swallow. Different teeth have different shapes for the different jobs they do. Some of our teeth are for biting, some are for tearing, and some are for grinding up the food. Everyone has the same types of teeth and they are found in the same spot in each person’s mouth.

Teeth have two parts. The crown of the tooth is the part that we see. The root of the tooth is the part that is below our gum line. The root keeps the tooth anchored in our mouths. The first set of teeth we have are called deciduous teeth. Children have 20 deciduous teeth, which are also known as baby teeth. Around age 6, our baby teeth start getting replaced by our second set of teeth. They start to fall out because they are getting pushed out by the second set of teeth, which are called permanent teeth. When all of our permanent teeth are finished growing, there are 32 permanent teeth.

Vocabulary: Child-Friendly Definitions

  • teeth — the hard, white objects in our mouths.
  • mirror — a smooth surface that shows an image of whatever is in front of it.
  • eggshell — the thin covering that encloses a bird’s egg.
  • stain — a spot or colored mark.
  • decay — to break down or become destroyed.
  • crown — the cover of the tooth; the part of the tooth that we see.

Lesson Tips

  • Making predications is a good way for children to engage in the scientific process. Explain that scientists often make educated guesses, or predictions, about what might happen then perform experiments to see if their predictions are correct. Encourage the children to communicate their discoveries to build their enthusiasm.
  • Caution the children that the toothbrushes used on the egg are being used in the art area for painting; therefore, they should not put them in their mouths. You can ask a local dentist to provide sample toothbrushes and toothpaste for the children to take home with them.


  • Brushing Teeth by Mari Schuh
  • Make Way for Tooth Decay by Bobbi Katz
  • Just Going to the Dentist by Mercer Mayer
  • The Tooth Book by Dr. Seuss

Home School Resources

Home educators: use these printable lesson PDFs to teach this lesson to your home schoolers. They're available in English and Spanish.

Home/School Connections

Las Conexiones a la Casa

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Content Provided By

Common Core State Standards Initiative – These lessons are aligned with the Common Core State Standards ("CCSS"). The CCSS provide a consistent, clear understanding of the concepts and skills children are expected to learn and guide teachers to provide their students with opportunities to gain these important skills and foundational knowledge [1]. Visit the CCSS