# What Is A Line Of Symmetry? Symmetrical Shapes Explained For Teachers, Parents and Kids

**In this post we will be answering the question “what is a line of symmetry?” and giving you all of the information you need to help your child understand this small, but key math concept! There are a few practice questions for your child to test their skills, so make sure you scroll all the way to the bottom of the blog.**

**What is a line of symmetry?**

A line of symmetry is a line that cuts a shape exactly in half.

This means that if you were to fold the shape along the line, both halves would match exactly. Equally, if you were to place a mirror along the line, the shape would remain unchanged.

A square has 4 lines of symmetry, as shown below.

An equilateral triangle has 3 lines of symmetry.

**Lines of symmetry in different symmetrical shapes**

Your child will learn all about the different shapes and their respective lines of symmetry, but here are some of the most common shapes.

**What will my child learn about lines of symmetry in school?**

Children are introduced to symmetry in elementary school, where they should be taught to identify and describe the properties of 2-D shapes, including the number of sides and line symmetry in a vertical line.

This is then developed when students identify lines of symmetry in 2-D shapes presented in different orientations and complete simple symmetric figures with respect to a specific line of symmetry.

Students will also be taught to recognize line symmetry in a variety of diagrams, including where the line of symmetry does not dissect the original shape.

**Symmetrical shapes (lines of symmetry) practice questions**

1) Here is a shape on a grid. Complete the design so that it is symmetrical about the mirror line. Use a ruler.

2) These two shapes are made from equilateral triangles. Draw one line of symmetry on each shape. Use a ruler.

3) Here is a grid with eight squares shaded in. Shade in two more squares to make a symmetrical pattern.

4) The letter D has a line of symmetry. Check **all** the other letters that have a line of symmetry.

**Wondering how to explain other key math vocabulary to your children? Check out our **Elementary Math Dictionary For Kids

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The content in this article was originally written by primary school teacher Sophie Bartlett and has since been revised and adapted for US schools by elementary math teacher Christi Kulesza.