Grades 2–3
Geometry
Lines of Symmetry
Objective: Identify lines of symmetry
in simple shapes and
recognize shapes with
no lines of symmetry.
Fold a piece of paper in half. Cut a shape in
the piece of paper but don't cut the side that
is folded.
Unfold the paper. What do you see?
The shape on one side of the fold should be
the mirror image of the other side.
Use a mirror to test whether this is correct.
Fold a new sheet of paper in a different way
or fold it twice. Cut out a different shape.
Unfold the paper. What has been reflected
this time? How is it reflected?
Draw the other half
of this shield.
Move the box to see if you're correct.
Now add the line of symmetry to the shield.
Can you spot any more lines of symmetry in the shield?
Draw the other half of these objects.
Add the line of symmetry. Is there more than one line?
Which object is the odd one out? Why?
© 2006 JupiterImages Corporation
© 2006 JupiterImages Corporation
© 2006 JupiterImages Corporation
© 2006 JupiterImages Corporation
© 2006 JupiterImages Corporation
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Title Page
Lines of Symmetry
Learning objectives
Getting Started
• Draw and complete
shapes with
reflective symmetry.
• Draw the reflection
of a shape in a line
of symmetry along
one side.
Open the “Lines of Symmetry” Notebook file and go to page 2. Give each student a
piece of paper and ask them to fold it in half. Ask them to cut a shape in the piece
of paper, keeping the fold intact. When they fold out the paper, they will see that
the shape on one side will be the mirror image of the other side. Use a mirror to test
whether this is correct.
Math Lessons for the SMART Board: Grades 2–3 © 2011, Scholastic
Resources
• “Lines of
Symmetry”
Notebook file
• mirrors with
straight edges
• sets of everyday
objects
• rulers
• paper
• scissors
Whiteboard tools
•
•
•
•
Pen tray
Select tool
Undo button
Delete button
Ask students to fold a new sheet of paper in a different way, or to fold it twice.
Tell them to cut out a different shape and open it out to show what they have
reflected. Review the terms mirror line and reflection from the previous lesson
(“Reflections,” p. 49).
Mini-Lesson
1. Go to page 3 of the Notebook file. Invite a student to draw the other half of the shield
(its reflection).
2. Move the box to reveal the hidden half of the shield. Establish that the shield is
symmetrical. Demonstrate this by holding a mirror to the line where the image is
exactly reflected, then draw that line in red along the mirror edge.
3. Cover half of the shield and cut that shape out of a folded piece of paper. Unfold it
and compare it to the shape on the board. Point out that the fold line is the line of
symmetry.
4. Ask students to find the lines of symmetry in their cutout shapes from the Getting
Started activity (above).
Independent Work
Divide the class into small groups and give each group a set of everyday objects. If the
object is 3D, state that for the purposes of this activity, students will need to choose
one side of the object to look at. Using a mirror, ask students to investigate whether
the different objects have one or more lines of symmetry. They should then sketch the
object and indicate the symmetry line using a ruler and a red pencil. If an object has
no lines of symmetry, students should draw it and write this fact underneath.
In the meantime, small groups can take turns at the SMART Board. Using page 4
of the Notebook file, invite students to draw the missing halves of the objects, deleting
or moving the boxes to see if they are correct. Invite them to add the line of symmetry
using the Pen tool and a real ruler laid on the SMART Board. Identify if there is more
than one line of symmetry or even none. Press the Undo button until the page is reset
and start the activity again for new groups.
Wrap-Up
Ask students to share what they have learned about lines of symmetry in their
investigation. Which objects have more than one or no lines of symmetry? Challenge
students to look for and make a list of examples of objects with one or more lines of
symmetry on their way home.
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