### Lesson plan

# Simply Symmetry!

#### Learning Objectives

- Students will be able to identify symmetrical figures, draw lines of symmetry, and explain why or why not a figure has symmetry.

#### Introduction

*(5 minutes)*

- Display the image of the butterfly.
- Ask the class to share some things they notice about the image. Some guiding questions you could ask are:
*What are the colors of the butterfly's wings? How are the wings shaped?* - Once students touch on the idea that the wings match in some way, introduce the word "symmetry." Explain that something has
**symmetry**if it can be split into two mirror-image halves. For example, a butterfly is symmetrical because you can fold a picture of it in half and see that both sides match.

#### Explicit Instruction/Teacher modeling

*(10 minutes)*

- Let your students know that the next activity will involve using a mirror to check figures for symmetry. Model the checking process before having students begin the activity.
- Hold up the construction paper heart, then hold up a mirror across its center to reflect its left half. Lift the mirror and ask students whether the reflection matches what's behind the mirror.
- Think aloud to confirm whether the figure is symmetrical. Ask and answer the following questions:
*The right half seems to match the reflection of the left half, but would the two halves match if I were to fold it? Are the two halves the same size and shape?*If the answer is yes for both, then the heart is symmetrical. - Check for symmetry in other directions by holding the mirror across different parts of the heart and repeating the process of thinking aloud.
- Show the class that the heart is only symmetrical in one direction. Fold the heart vertically and horizontally to show where the halves match and do not match.
- Place a piece of bright colored yarn across the vertical fold. Explain that the piece of yarn, which marks where you held the mirror and made the proper fold, represents the heart's
**line of symmetry**. - Refer back to the butterfly image and show how the butterfly's line of symmetry runs vertically down the middle of its body.
- Repeat the modeling process for the triangle and square, placing pieces of yarn across their lines of symmetry.

#### Guided Practice

*(15 minutes)*

- Organize the class into groups of 2-3 students. Give each group a hand mirror, a bag of shapes, and some yarn pieces.
- Have the groups repeat the process you modeled to check their shapes for symmetry.
- After about 10 minutes, pause the activity. Have different groups share what they've found thus far.
- As each shape is discussed, reinforce why it does or doesn't have symmetry.

#### Independent working time

*(10 minutes)*

- Have students continue the activity independently.

#### Differentiation

**Enrichment:** Have advanced students examine more complicated figures during Independent Working Time. You can give each student half an image of a symmetrical figure found in nature (e.g. a leaf or flower) and ask him to draw the other half on a sheet of paper.

**Support:** Help struggling students by folding some of their shapes for them. This will help them see where the line of symmetry usually lands.

#### Technology Integration

An interactive whiteboard may be used to display different shapes and draw lines of symmetry.

#### Assessment

*(5 minutes)*

- Distribute sheets of lined paper to the class.
- Have each student write three sentences defining symmetry and line of symmetry.
- Under those sentences, have students write whether they think a star would have symmetry. Remind them to explain their reasoning.

#### Review and closing

*(10 minutes)*

- Review the concept of symmetry once again, repeating its definition and demonstrating it using a symmetrical shape.
- Have students partner up and think of examples of symmetrical figures.
- Close the lesson by allowing volunteers to share examples given by their partners.