Teacher sheet · Ages 10–11 · about 45–50 minutes
Inside a tooth and how decay happens
Lesson page: echoesof.science/school/teeth/ages-10-11/ · Pupil worksheet: echoesof.science/school/teeth/ages-10-11/print/
Learning aims
- Name the four kinds of teeth and their jobs.
- Label the parts of a tooth.
- Explain how bacteria, sugar and acid cause decay, and how enamel repairs.
- Plan and carry out a fair test with a control.
Lesson plan
| Time | Activity |
|---|---|
| 5 min | Starter: bite an apple slice. Which teeth did you use to bite and which to chew? |
| 10 min | Read the text; label a tooth diagram. |
| 20 min | Plan and set up the drinks fair test. |
| 5 min | Game: Name the part. |
| 5 min | Quiz. Next day: 15 minutes to observe and conclude. |
Materials for the experiment
- 5 hard-boiled eggs (cooled)
- 5 clear cups, labelled
- The same volume (for example 200 mL) of: water, milk, cola, orange juice, white vinegar
- Measuring jug
- Kitchen roll
- A magnifying glass
Safety: Use hard-boiled, cooled eggs; an adult does the boiling. Do not eat the eggs or drink from the cups afterwards. Vinegar stings in eyes: wash hands after handling. Check for egg and milk allergies. Pour the drinks away down a sink at the end.
Common misconceptions
| Pupils may think… | Actually… |
|---|---|
| Teeth are dead and cannot change. | The pulp has nerves and blood vessels, and enamel loses and regains minerals all the time. |
| Holes appear suddenly. | Decay starts as mineral loss (a white spot) after many acid attacks and can be stopped early. |
| Only the amount of sugar matters. | How often we eat sugar matters too: each snack is another acid attack. |
Worksheet answers
- Crown above the gum, root below; enamel as the outer layer of the crown; dentin under it; pulp in the centre.
- Bacteria in plaque use sugar to make acid; the acid takes minerals out of the enamel; after many attacks a cavity forms.
- Changed: the type of drink. Measured/observed: bubbles and the state of the shell. Kept the same: volume of drink, time, size of egg, temperature (any two).
- For example: brush twice a day with fluoride toothpaste and spit, don't rinse; have fewer sugary snacks between meals.
Quiz answers
- How many molars can an adult have, including wisdom teeth? 12. There are 12 molars; the third molars are the wisdom teeth.[5]
- Which part of the tooth contains nerves and blood vessels? The pulp. The pulp in the centre holds nerves and blood vessels.[5]
- What is plaque? A sticky film of bacteria. Plaque is a sticky, colourless film of bacteria.[3]
- Where does the acid that attacks teeth come from? Bacteria using sugars. Bacteria use sugars in food to make acids.[2]
- Which helps enamel to repair itself? Minerals in saliva and fluoride. Calcium and phosphate from saliva and fluoride help enamel regain minerals.[3]
- In the eggshell test, why do we keep one egg in water? It is the control, to compare with. A control shows what happens without the acid drinks.[10]
Going further
Repeat the test with an egg that was first coated in fluoride toothpaste for a day, then put in vinegar. Does it bubble less than an uncoated egg?
Sources used in this lesson
- [2] The Tooth Decay Process: How to Reverse It and Avoid a Cavity (National Institute of Dental and Craniofacial Research (NIH, USA)): reliability High
- [3] The Tooth Decay Process (children's oral health) (National Institute of Dental and Craniofacial Research (NIH, USA)): reliability High
- [4] Tooth (anatomy) (Encyclopaedia Britannica): reliability High
- [5] Anatomy and Physiology 2e, 23.3 The Mouth, Pharynx, and Esophagus (OpenStax, Rice University (Oregon State University open edition)): reliability High
- [6] Community Water Fluoridation: Frequently Asked Questions (Centers for Disease Control and Prevention (USA)): reliability High
- [10] ChemShorts for Kids: eggs, soda and tooth enamel (Chicago Section of the American Chemical Society (ChemShorts series by Paul Brandt)): reliability Medium-high
- [11] Dental health and acid science experiment (teeth.org.au (Australian dental health education site; the PDF does not name its author)): reliability Medium
Full list with links and a note on each source's reliability: echoesof.science/school/teeth/sources/
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