Math Background

Lesson: Identify Plane Shapes and Solid Shapes
Introducing the Concept

Your children were formally introduced to plane shapes in Kindergarten. Now they will sort and classify plane shapes by the number of sides, number of corners, and size.

Materials: red, yellow, and blue construction paper circles; a set of four basic plane shapes (circle, square, rectangle, triangle) for each child (use small attribute blocks or the smaller shapes from Learning Tool 27 in the Learning Tools Folder), a larger version of the four basic plane shapes for every child or pair of children (use large attribute blocks or the larger shapes from Learning Tool 27); chart paper

Preparation: To review position words, cut out construction paper circles so that each child will have one and so that the colors will be as evenly divided as possible. If using Learning Tool 27, copy and cut out shapes. You may want to put each set of shapes in an envelope so you can easily give them to the children.

Prerequisite Skills and Concepts: none

Begin by reviewing position words with the class. Have children work in groups of three. For each group, give one child a yellow circle, one a red circle, and one a blue circle. Then, using position words such as between, below, left, and right, give instructions on how to arrange the circles in relation to one another. Tell children that they will next work with their circles and other shapes.

  • Ask: When we talk about shapes we will talk about how many sides and corners they have. Can anyone tell me what a side is?
    Elicit that a side is a straight line that is part of a shape.
    Give each child a set of shapes.
  • Say: Look at this shape. (Hold up a square.) Find this shape in your set and run your fingers along any side of it.
    Model this with your square.
  • Ask: How many sides does this shape have?
    Children should say the shape has four sides.
  • Ask: Now I want to know how many corners this shape has. Who can tell me what a corner is?
    Elicit that a corner is where two sides meet. Relate this to the idea of a street corner, a corner of a desk, or a corner of a room. Hold up the square again.
  • Ask: How many corners does this shape have? (4) Does anyone know the name of this shape?
    Have a volunteer say that the shape is a square. List the number of corners and sides on the chalkboard for each shape. Hold up a rectangle and ask children to tell the number of sides and corners and the name of the shape. Then hold up the square and the rectangle next to each other.
  • Ask: How are these shapes the same?
    Children should say they both have four sides and four corners.
  • Ask: How are they different?
    Elicit that the square's sides are all the same length. Only opposite sides of the rectangle are the same length.
  • Say: A square is a kind of rectangle with sides that are the same length. Now let's look at another shape.
    Tape the square, the rectangle, and a triangle to the chalkboard. Tape the square and the rectangle a little apart from the triangle.
  • Ask: How is this shape (pointing to the triangle) different from the square and the rectangle?
    Elicit that the triangle has only three sides and three corners. List these attributes on the chalkboard.
  • Ask: Does anyone know the name of this shape?
    A volunteer should say that it is triangle.
  • Ask: The first part of the word triangle, tri-, means “three.” Can you think of something you ride on that has three wheels? (a tricycle)
    Tape the circle to the board.
  • Ask: How many sides does this shape have? (none) How many corners? (none) What is this shape called? (a circle)
    On the chalkboard, list that there are no sides or corners in a circle.
  • Say: Circles have no straight lines, so they have no sides or corners.
    Direct children's attention to the chalkboard list.
  • Ask: What do you notice about the number of sides and the number of corners a shape has?
    Elicit that the number of sides is the same as the number of corners.

    Have children find a partner. Have one partner trade his or her set of shapes for a set of larger shapes. Tell children to combine sets with their partners.

  • Say: Now we are going to think about ways to sort shapes. I want you to work with your partner to think of at least two different ways to sort your shapes.
    Give children a few minutes to complete the task. While they do so, remove the shapes from the board.

When the children are done, have volunteers share one way in which they sorted their shapes. While one partner explains the attribute by which they sorted, have the other tape the shapes in their appropriate groups onto one of the pieces of chart paper. At the top of each paper, label how the shapes are sorted. Possible attributes by which to sort are size, shape, number of sides, and number of corners. You may wish to display the completed charts.


Houghton Mifflin Math Grade 1