• Plastic drinking straws with flexible joints
• Toothpicks or pretzel sticks and gumdrops or marshmallows
• Paper nets of solid figures
• Solid figure models

"Building a model of a three-dimensional shape is an informal way to get to understand the shape intuitively in terms of its component parts."¹

When students build 3-dimensional models they are actively engaged in examining the parts, the number of parts and the arrangement of parts of each figure. These constructed 3-dimensional models (or solid figure models) can then be used to compare and contrast the various solid figures in terms of vertices, edges, faces and bases.

• Students can build skeletal models of three-dimensional shapes using rods of some sort. Suggested materials to use:
  - Plastic drinking straws with bendable joints
  - Toothpicks or pretzel sticks to represent the edges. Use gumdrops or miniature marshmallows to represent the vertices.
   

• Give the students small paper squares and tape. Working in pairs or small groups, the students should find as many different arrangements (nets) as possible for six squares. As they complete a net, they will tape the squares together and determine whether the net, when folded, forms a cube.

  Note: A net is an arrangement of polygons that can be folded into a geometric solid.

  Example:

  

  
   
• Make a copy of each of the following nets for the students. Working in pairs or small groups, have student construct the different geometric solids. As students are working, discuss the shape of the faces. When the solids are constructed, have students discuss the number of faces, edges, and vertices.

  

  
   
• Give students triangular and rectangular pyramids, triangular and rectangular prisms – if possible use several examples of different sizes. Have them work in groups to find similarities and differences of the two pyramids. Have students form a definition of each pyramid. Compare the definitions from each group to generate a class definition.

  Rectangular Pyramid Model 1

  

  Rectangular Pyramid Model 2

  

  Triangular Pyramid Model

  

  Rectangular Prism Model

  

  Triangular Prism Model

  

  
   

¹Van de Walle, John, Elementary and Middle School Mathematics, Teaching Developmentally, 4^th Edition, Longman, 2001.