1. Science - Year 3/4B Summer 1
Animals including humans
The Circle of Life
Session 3
Teaching PowerPoint
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2. Here is a model of a set of teeth
Are all the teeth the same size and shape?
No!
Different types of teeth have different jobs to do

3. The teeth at the very front of your mouth are for biting.
These teeth have a long narrow biting surface and they are called incisors. There are usually 4 at the top and 4 at the bottom.

4. Can you find the incisors?
Here is a model set of bottom teeth. The jaw bone and gums are made from a transparent (see-through) material so you can see the roots of the teeth as well.
Can you find the incisors?
Don’t worry if you have some gaps! Your adult incisors will grow soon!
How many incisors do you have?
Use the mirror and your tongue to check out your incisors

5. Next to your incisors are the 4 teeth on the corners of your bite
Next to your incisors are the 4 teeth on the corners of your bite. They are more pointed.
These teeth are called canines
Use the mirror and your tongue to try to find your canines

6. Which ones are the canine teeth?
Here are the incisors shown by the red arrows on this model set of bottom teeth.
Which ones are the canine teeth?
What do you think these pointy teeth are for?
Here’s a clue:
Dogs have much bigger canine teeth than us!
Answer:
They are for gripping and tearing tough chewy food like meat

7. Chewing – which means crushing and grinding food into small pieces
Now we know that incisors are for biting and canines are for gripping and tearing, but what are all the other teeth for?
Incisors
Canine
Answer:
Chewing – which means crushing and grinding food into small pieces
Did you know?
The human jaw has an amazing crushing power of up to 85kg!
85kg

8. There are 2 kinds of chewing teeth
There are 2 kinds of chewing teeth. They are called premolars and molars.
Incisors
Canine
Premolars are next to the canine teeth. They are smaller than the molars and the crown has 2 points (see yellow arrows).
Premolar
The crown of the tooth is the part that is visible
The root is inside the jaw beneath the gums. It holds the tooth in place.
This set has 4 premolars

9. The large chewing teeth at the very back of the mouth are called the molars.
Incisors
Canine
Premolars
Molars
Molar
Molars have a crown with 4 points (see yellow arrows)

10. Use a mirror to take a look at your back teeth and take a look at your partner’s back teeth too.
Can you find premolars and molars?
What is the difference?
What job do they do?
How does their shape help with this?

11. Does everyone have the same number of teeth?
No!
Babies are usually born with no teeth at all but they begin to emerge through the gums when they are a few months old. There are 20 first teeth (often called milk teeth) which are gradually lost and replaced by a set 32 adult teeth.
Use the mirror once again to check out your teeth. Can you tell which are first teeth and which are adult teeth?
Your adult teeth are larger. They will probably be a creamier shade of white and have little ridges on the biting edges.

12. Why is it important that you take care of your teeth?
Your mouth contains bacteria that feed on the sugary remains of food and drink. The bacteria produce acid that dissolves the hard coating (called enamel) around the outside of the teeth. This is called tooth decay.
But the good news is, you can brush away the sticky film (called plaque) caused by bacteria and sugar which builds up on your teeth. Toothpaste will neutralise the acid and strengthen the enamel.
Keep away tooth decay by:
Brushing your teeth thoroughly every morning and evening
Avoiding sugary snacks and drinks
Visiting the dentist for regular check ups