An overview of the properties of polyhedrons, prisms and pyramids

Published on: **Mar 4, 2016**

- 1. Let’s go to the ballet 0 See if you can accurately name all the shapes
- 2. Polyhedrons Polyhedrons Pyramids Prisms Pyramids Prisms
- 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
- 6. 3D Shape Properties
- 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
- 8. What does that mean?
- 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
- 13. Other 3D shapes
- 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?