Grade: 3-5
Subject: Mathematics

#4750. Line of Symmetry

Mathematics, level: 3-5
Posted 02/17/2014 by Catherine Balmeo (Catherine Balmeo).
LIncoln Public School, Lincoln, USA
Materials Required: pre cut regular shapes
Activity Time: 30-40 minutes
Concepts Taught: symmetry


Objectives:Analyze geometric figures and pictures in order to identify and describe symmetry

Levels of Cognitive Demand: Level2, Application Analysis

Whole group: I DO/teacher
1. Review identifying congruent figures [congruent figures are figures with the same shape and same size]. Have a student put his/her palms together. Have a volunteer describe the hands {have same shape and same size]. Distribute shapes of the same size and shape for the students to explore the concept of congruent.

2. Have the children cut out symmetrical figures ex. Heart, diamonds---explain to the children that figure is symmetric because the 2 halves of the figure are congruent. The folded line is the line of symmetry.

The shape can have more than 1 line of symmetry e.g. circle folded in different direction can have multiple lines of symmetry.

Have students identify the line of symmetry. Distribute pre-cut regular shapes and letters [B,H, E, D,C]. Teacher will direct students to fold the polygon by folding the corners and edges together to form a straight crease. Have the students trace the crease and that line is the line of symmetry. For the letters, have the students fold the letters horizontally to form symmetric parts.

Complete the table:

shape Number of lines of symmetry
square 4
rectangle 2

INDEPENDENT: YOU DO/student's turn

1.Have students work in pairs. Have one student draw half of a figure and a partner draw the other half to make the figure symmetric.

2. Have the students use a sentence frame to explain their answer on whether a figure is symmetrical or not.

Sentence Frame:
_____________ is symmetrical because __________
_____________ is not symmetrical because ______

Word Bank:
*Symmetrical figures have congruent halves.
*Two halves are not congruent.