## Lesson: Plane Shapes and Solid Shapes Introducing the Concept

Help with Opening PDF Files

Provide children with a number of experiences in which they can practice using and identifying plane and solid shapes. Begin by having children match shapes, first by type and then by size. Encourage them to use the names of both plane and solid shapes in their conversation and class discussion. Have children practice holding, looking at, and then describing shapes by their attributes. Provide enough experiences so that children feel comfortable with simple plane and solid shapes and their attributes.

Materials: two sets of cut-out plane shapes (Worksheet 1 (PDF file), Worksheet 2 (PDF file)) for each child; objects such as a small rubber ball, an eraser in the shape of a rectangular prism, a cube-shaped box, a can, a party hat, a pyramid

Preparation: Copy Worksheet 1 (PDF file) and cut out the shapes for each student. Make a copy of Worksheet 2 (PDF file) for each child. Gather examples of solid shapes as listed above.

Prerequisite Skills and Concepts: Children should be familiar with the names of solid and plane shapes.

• Say: Look at the shape labeledA.
• Ask: How many sides does this shape have?
Have a volunteer provide the answer. (4) Make sure children understand that a side is a straight line that makes part of a shape.
• Ask: How many corners does this shape have?
Have a volunteer provide the answer. (4) Explain to children that each corner is called a vertex. Encourage children to volunteer that Shape A has 4 vertices.
• Ask: What is the name of this shape?
Have a volunteer tell that the shape is a square.
• Ask: How do you know it's a square and not a rectangle?
Children may note that a square has 4 sides all the same length.

Repeat this procedure with plane shapes A-F from Worksheet 1 (PDF file). Tell children to put Shapes G and H aside for use later in the lesson.

Provide sets of solid shapes to small groups of children. Then distribute Worksheet 2 (PDF file).

• Say: You have described plane shapes by counting the sides and vertices. Now let's see how we can describe solid shapes. These objects are examples of solid shapes. Each one matches a solid shape on your worksheet.

Hold up the cube-shaped box for children to see.

• Ask: Which shape does this box match?
Have children circle the correct shape on Worksheet 2 (PDF file). Then ask a child to tell the number of the shape he or she circled. Encourage children to tell the name of the shape. (cube) Provide the answer if children do not volunteer it.

Define the terms face and edge. Hold up the box again.

• Ask: How many faces does the box have? (6) How many edges does it have? (12)
For each question, have children count and record the answers on Worksheet 2 (PDF file).

Repeat this procedure for each of the solid objects, making sure that children can match each object with the correct shape on Worksheet 2 (PDF file), tell how many faces and edges the shape has, and name the shape. Record the answers.

Write the words congruent and line of symmetry on the board.

• Say: Here are some other terms we can use to describe plane shapes.
• Ask: Now let's look at Shapes A-F again. Which of the shapes are the same size and shape? Have children volunteer the answers. (Shapes C and F) How can you tell? (If you put them on top of each other, they match exactly.)
• Say: Shapes that are the same size and shape are calledcongruent shapes.
• Say: Sometimes a shape can be folded into matching, equal parts. Then we say the shape has aline of symmetry. Think of the fold as the line of symmetry.

Tell children to look at Shapes G and H.

• Ask: Do these shapes have lines of symmetry? Have a volunteer answer. (yes) How can you tell? (If you fold them in half, the two sides match exactly.)

Ask children to look at Shapes A-F and tell which ones have lines of symmetry. (A, C, D, E, F). Have a child explain why Shape B does not have a line of symmetry. (When you fold it in half, the two sides do not match.)

Demonstrate how the rectangle has two lines of symmetry. Challenge the children to find the shapes with more than one line of symmetry. (A, C, D, E, F, G)