Math Background

Lesson: Identifying and Classifying Solid Figures
Introducing the Concept

Use this activity to introduce students to the names and attributes of solid figures.

Materials: 1 solid figure for each student, a table for displaying the solid figures, 6 index cards

Preparation: Have students bring in objects from home that look like solid figures; for example, empty cereal boxes, cans, party hats, etc. Give each student one object. Write the name of a solid figure on each index card: rectangular prism, cube, sphere, cone, cylinder, pyramid.

Prerequisite Skills and Background: Students should understand the concept of plane figures and know the names of polygons.

  • Say:Figures that are not flat like plane figures are called solid figures.
  • Ask:Who has a solid figure that can roll?
    The students who have spheres, cones, or cylinders should respond.
  • Ask:Who has a solid figure that can roll no matter how you place it on your desk?
    The students who have spheres should respond. Have them place the spheres in a group on the display table.
  • Say:These solid figures are called spheres.
    Tape the card labeled sphere on the wall above the spheres.
  • Say:Let's look closer at the surfaces of the other solid figures that can roll. They have both curved surfaces and flat surfaces. The flat surfaces are called faces.
  • Ask:What shape are the faces of these solid figures? (circle)
  • Ask:Who has a solid figure that has one face that is a circle?
    The students who have cones should respond. Have them place the cones in a group on the table.
  • Say:Solid figures that have one face that is a circle are called cones.
    Tape the card labeled cone on the wall above the cones.
  • Ask:Who has a solid figure that has two faces that are circles?
    The students who have cylinders should respond. Have them place the cylinders in a group on the table.
  • Say:Solid figures that have two faces that are circles are called cylinders.
    Tape the card labeled cylinder on the wall above the cylinders.
  • Ask:Who has a solid figure whose faces are polygons?
    The students who have rectangular prisms, cubes, or pyramids should respond.
  • Ask:Who has a solid figure that has three or more faces that are triangles?
    The students who have pyramids should respond. Have them place the pyramids in a group on the table.
  • Say:Solid figures that have three or more faces that are triangles are called pyramids.
    Tape the card labeled pyramid on the wall above the pyramids.
  • Ask:What type of polygons are the faces on the other solid figures?
    Students should realize that they are all quadrilaterals.
  • Ask:Who has a solid figure that has six square faces?
    The students who have cubes should respond. Have them place the cubes in a group on the table.
  • Say:Solid figures that have six square faces are called cubes.
    Tape the card labeled cube on the wall above the cubes.
  • Ask:Who has a solid figure with four or more faces that are rectangles?
    The students who have rectangular prisms should respond. Have them place the rectangular prisms in a group on the table.
  • Say:Solid figures that have four or more faces that are rectangles are called rectangular prisms.
    Tape the card labeled rectangular prism on the wall above the rectangular prisms.
  • Ask:Why is a cube also a rectangular prism?
    Students should respond that the faces of a cube are squares, and squares are rectangles.
  • Use the solid figures on the table daily to help students recognize them and learn their names.
Houghton Mifflin Math Grade 3