3. Lesson Objectives
0 To understand the differences between platonic
solids, prisms and pyramids
0 To examine the properties of polyhedrons
0 To develop your own NET shapes using 3D shapes
provided
4. Polyhedrons
0 Poly = Greek for many
0 Hedron = Greek for face
0 Polyhedron = Many Faces!!
5. Likely Difficulties
0 Names for 2D figures and 3D objects often get
confused because the beginning of names are
similar…
0 Dodecagon = 12 sided 2D shape
0 Dodecahedron = 3D 12 sided regular pentagon
7. Platonic Polyhedrons
0 Plato, a Greek philosopher and
mathematician.
0 Worked out that some polyhedrons are identical in
shape and size.
0 Edges = Same length
0 Angles = Same size
0 Vertices = Identical
9. Platonic Polyhedrons are
Perfect!
0 All vertices are surrounded by the same plane shape.
0 Any face can be the base.
0 They are beautifully symmetrical.
0 Only five of them exist!
10. Platonic
Solid
Picture
Number
of Faces
Shape of
Faces
Number
of Faces
at Each
Vertex
Number
of
Vertices
Number
of Edges
Unfolded
Polyhedron (Net)
Tetrahedron 4
Equilateral
Triangle
(3-sided)
3 4 6
Cube 6
Square
(4-sided)
3 8 12
Octahedron 8
Equilateral
Triangle
(3-sided)
4 6 12
Dodecahedron 12
Regular
Pentagon
(5-sided)
3 20 30
Icosahedron 20
Equilateral
Triangle
(3-sided)
5 12 30
11. Pyramids & Prisms
0 Prisms have two identical, parallel faces joined to one
another by rectangles. Examples are;
12. Pyramids & Prisms
0 Pyramids have one face with at least 3 edges, the faces
meeting these edges are ALL triangles.
0 NOTE: Pyramids get their name from the shape of their
base
0 There are many more pyramids than these ones shown
14. Activity!
0 You will be given some examples of 3D shapes
0 Name the shapes you have been given
0 With your elbow partner, use the graph paper
provided to draw a NET of the shapes you have been
given
0 Cut out the Nets you have drawn and see if they can
be made into the original 3D shapes (you might want
to leave a lip on some sides so you can glue it
together)
0 Did you get it right? If not, what do you need to
change to make it correct?
Editor's Notes
Note: Get the students to name shapes at the end of the video – lasts for 1 minute 38 seconds
NOTE: 2D figures have sides – 3D objects have faces and edges – a corner is called a vertex
NOTE: students could copy this down or it can be printed from the associated document
EXTENSION: Give students four cubes and ask them to draw a net shape for this cube combination using the least amount of paper and without making nets of four separate cubes and sticking them together. (cube combo – 3 cubes on base and one cube on top of middle base cube)
