Lines Of Symmetry Lesson for Third Grade Math Students

Teaching Third Graders about Symmetry

Materials Needed

You will need several items for teaching this lesson.

• A large drawing of a symmetrical butterfly, slightly bent along its line of symmetry
• A number of cut-out shapes, half symmetrical, half asymmetrical
• A piece of construction paper for each student
• Crayons, colored pencils or colored markers for each student
• Each student also needs a pair of scissors
• Paper for each student that has a square divided into a 6x6 grid of 1-inch squares, with the center horizontal and vertical lines darker than the rest

Get the Students Interested

Ask the children if they know what a lepidopterist is. (Someone who studies butterflies and moths.) Tell them they don't have to remember the word, but if they do, their parents will be very impressed! Then ask them to pretend they are lepidopterists and that you are, too. Show them the large butterfly, and tape it to the top of the board. Allow the children to tell you some things they observe about the butterfly.

Teach with a Game

Draw two columns on the board. Label one 'Shapes Our Butterfly Likes.' Label the other column 'Shapes Our Butterfly Doesn't Like.' Tell the students they are going to play a butterfly game and no one except you can speak during the game or they may scare the butterfly.

Put a symmetrical shape in the like column and say, 'The butterfly likes this kind of shape.' Put an asymmetrical shape in the doesn't like column, saying, 'The butterfly doesn't like this kind of shape.'

Remind the class that they mustn't talk during this game. Ask them to raise their hand if they think they can see a pattern for what kinds of things the butterfly likes and doesn't like. Continue putting shapes on the board, reminding them to be silent, and asking if they can see a pattern. Keep doing this until either everyone raises their hands or you run out of shapes to add.

Ask one child to identify the pattern. If necessary, keep doing this until someone gets it correct. Help the class to come up with a definition of symmetry; write the definition on the board and have the children write it down, too.

Show them that the butterfly likes these shapes because they are symmetrical. Remove the butterfly from the board and fold it along its line of symmetry, showing them how the edges match and pointing out that the lines, spots and colors on the wings also match. Take the shapes from the columns and fold them to show that they do or do not have lines of symmetry. Allow the children to do some of them.

Activities

Make Their Own Butterflies

Give the children a piece of construction paper and have them fold it in half. Point out that the piece of paper is symmetrical. With the paper still folded, the children will draw the outline of half of a butterfly, with the body on the fold. The children should then cut the butterfly out and open it up. They now have a symmetrical butterfly. Explain that it is too hard to draw and color spots freehand on the butterfly and make it truly symmetrical, so you have something else they can make.

Make Quilt Patterns

Give each child a paper with the 6x6 grid on it. Show them a sample one on which you have colored just one of the quarters of squares (3x3), with each 1-inch square brightly colored. Ask them to do the same on their papers using at least two colors.

When they have finished, make the colors symmetrical on your next 3x3 quarter, and describe what you are doing each step of the way. The children do the same on their papers. Continue on with the third quarter and then the fourth.

Wrap It Up

Talk about the horizontal and vertical lines of symmetry on their quilt patterns. If none of the children notice it, show them that they have diagonal lines of symmetry, too. Wave goodbye to your butterfly. Have the class do the same with their butterflies and put them away. Compliment them on what excellent Lepidopterists they have been. (Because you have used the term lepidopterist so frequently, many of the children will remember the term and can amaze their parents and siblings.)