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TouchMath Extend

Lesson 46: Corners and Edges

Lesson Objectives

  • Define 2-D shapes by their attributes 
  • Compose 2-D shapes using concrete objects and pictorial representations 
  • Sort and classify objects 


  • Extend Workbook (Page 46) 
  • 2-D shapes manipulatives 
  • Highlighters, markers, or crayons 
  • Whiteboards and dry erase markers 

Step 1: Warm Up (5 min)

Review each type of shape listed on the student activity sheet on page 46, based on number of sides, edges, and corners. Circles: 1 edge and 0 corners (it is a curved line that joins where it begins. Triangles: 3 edges, 3 corners, 3 sides. Squares: 4 edges, 4 corners, 4 sides. Pentagon: 5 edges, 5 corners, 5 sides. Hexagon: 6 edges, 6 corners, 6 sides.

Step 2: Vocab Review (5 min)

Introduce new vocabulary: open and closed shapes, edges, lines, corners. Explain that all shapes are either open or closed. They are closed if the lines connect or meet. Circles, triangles, rectangles, sequares, pentagons, and hexagons are all closed shapes. These are all described by the number of edges, or lines, and the number of corners, or angles.

Step 3: Model (5 min)

Remind students that shapes can be different sizes and colors – the size and color do not make them for example a circle, the number of edges and corners makes it a circle (or not). Draw several circles, triangles, and squares of different sizes. Color all the circles one color, triangles another, and squares a different color. Explain the different in each shape but reiterating that it does not matter if they are different sizes and colors – for example, a triangle will always be a triangle if it has 3 edges, 3 corners, and 3 sides.

Step 4: Guided Practice (5 min)

Ask students to draw a circle, triangle, and square and to label how many edges and corners they have, as well as sides. Students can work in pairs to continue this activity for pentagons and hexagons. Then, draw a shape on the white board, and in pairs, ask students to decide what shape it is, and to list how many edges and corners it has. Continue this activity for each shape: circle, triangle, square, pentagon, and hexagon. 

Step 5: Student Practice (5 min)

Go to Student Workbook Page (46). Read the directions. Ask students to identify how many edges and corners each shape has and to write their answers on the lines provided for each shape. 

Step 6: Wrap Up (5 min)

To wrap up the lesson, review the learning objectives and core vocabulary words again and ask your students about their experience.