Fold It in Half: Lines of Symmetry

About This Resource

A free Grade 4 math worksheet on lines of symmetry: a line that splits a shape into two matching halves, like a fold or a mirror. Students count the lines of symmetry in squares, rectangles, triangles, kites, rhombuses and regular polygons, find symmetry in capital letters and everyday objects, notice that a regular polygon has as many lines as sides, and draw their own symmetrical shape. Includes a timed lesson plan, a six-activity worksheet, an editable Word version and answer key.

Overview

Students learn that a line of symmetry divides a shape into two halves that match exactly, so if you fold the shape along the line, one half lies perfectly on top of the other. They test shapes by folding paper and using small mirrors, count the lines of symmetry in common 2-D shapes, and discover that a regular polygon has the same number of lines of symmetry as it has sides. They look for symmetry in capital letters and in objects around them, and finish by drawing a shape with exactly one line of symmetry.

Resource Details

Subject: Math
Topic: Lines of Symmetry
Category: Shapes & Geometry
File Type: PDF
File Size: 268.2 KB
Published: 08 Nov 2026
Downloads: 1

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Grade 4 math (ages 9–10) 45 minutes Geometry spatial reasoning checking with folding and mirrors explaining

Student Task

Fold a paper square in half in different ways. Ask: "Do the two halves match exactly?" Mark each fold that works.
Do activities 1 and 2 together, folding paper shapes or using a mirror to check.
Students complete activities 3 to 6 on their own. Answers are in the answer key.

Classroom Use

Fold and check: give each pair paper shapes (square, rectangle, equilateral triangle, parallelogram) to fold and count lines of symmetry.
Mirror test: stand a small mirror on a line in a shape; if the picture looks complete, the line is a line of symmetry.
Symmetry hunt: students walk around the classroom and list objects that are symmetrical.

Differentiation

Support: give students paper cut-outs of every shape to fold. Challenge: students investigate how many lines of symmetry a regular decagon (10 sides) has and explain the pattern.

Answer Key & Assessment

Activities 1 to 5 check counting and identifying lines of symmetry (answer key included). Activity 6 shows whether students can draw a shape with one line of symmetry.

Learning Objectives

Explain what a line of symmetry is.
Count the lines of symmetry in common 2-D shapes.
Identify symmetry in letters and everyday objects, and draw a symmetrical shape.

Teacher Tips

Many students think a rectangle has four lines of symmetry because a square does. Let them fold a paper rectangle along a diagonal: the corners do not match, so the diagonal is not a line of symmetry.

What's Included

7-page printable PDF lesson pack: teacher lesson plan with timings, materials and differentiation
Key vocabulary list (6 words with meanings and examples)
Student worksheet (6 activities)
Editable Word version of the worksheet
Complete answer key (also as a separate PDF)