A prism is a solid shape that has two key properties: 1) It has a constant cross-sectional shape along its entire length, where the cross-section is the same shape as the base. 2) It maintains the same size and shape of any slices cut parallel to its base, from the base to the top. To test if an object is a prism, we can imagine slicing it from the base to the top - if all the slices are the same size and shape, it is a prism. Prisms can be thought of as being made up of stacked layers or slices of equal height. The volume of a prism can be calculated by multiplying the area of its base by the number of layers or

1. PRISMS
• A prism is a solid with a constant cross section
in one direction. The cross section has the
same shape as the base.

2. PRISMS
It doesn't matter
which way a
prism is facing, (or
which of its faces is on the
bottom), we always
refer to the cross
sectional shape is
“the base”.

3. THE CHEESE TEST
• To test whether an object has a constant cross
section, we start taking slices from the base, all the
way to the top.
If all the slices are the same size and shape – it’s a
prism!

4. THE CHEESE TEST
PRISM
(if we slice this block the right
way, all these slices will be the
same)
NOT A PRISM
(the shape of these slices will
change, no matter which way you slice
it)

5. THE CHEESE TEST
NOT A PRISM
(if we slice this cone, every slice
will be a different size…)
PRISM
(this cylinder can be sliced so that
every slice is the same size and shape)

6. LAYERS
• We can imagine that every prism is build up of
layers: Slices that are one unit high.
BASE LAYER:
Area = 8 units2
Height = 6 units
(6 layers)
What would the volume of this prism be?

7. LAYERS
• What is the base area of each of these
prisms?
• How many layers are there in each?
• How could we find the Volume?

8. WHICH OF THESE SOLIDS ARE PRISMS?

9. You’re ready to take on the ACE OF BASE QUIZ in lesson 3…