Identifying lines of symmetry in 2D shapes and completing symmetrical figures.
Where your child meets this in real life: Recognising symmetry in logos, flags, butterflies, and architectural designs
SEAGReady breaks lines of symmetry into 3 steps, taught in order so each skill builds on the last.
Identify a vertical or horizontal line of symmetry in common 2D shapes
Find all lines of symmetry in shapes including diagonal lines
Complete a shape by drawing its reflection across a given mirror line
Three free sample questions from our lines of symmetry course. Every question comes with a full explanation, and hints that guide without giving the answer away.
Sean is designing a badge for his scout group. He draws an isosceles triangle. Does the isosceles triangle have a line of symmetry?
Answer: A. Yes, one vertical line from the top vertex to the middle of the base
An isosceles triangle has two equal sides. If we draw a vertical line from the top vertex down to the middle of the base, we can fold the triangle along this line. Both halves would match exactly, so this is a line of symmetry. Answer: Yes, one vertical line from the top vertex to the middle of the base.
Stuck? Start here: Think about folding the triangle - where could you fold it so both halves match exactly?
Declan is making a tile pattern using squares. He wants to find all the lines of symmetry in a square. How many lines of symmetry does a square have?
Answer: A. 4 lines of symmetry
A square has 4 lines of symmetry: - 1 vertical line through the middle - 1 horizontal line through the middle - 2 diagonal lines from corner to corner Each of these lines creates two matching halves when folded. Answer: 4 lines of symmetry.
Stuck? Start here: Think about all the ways you could fold a square so both halves match.
Roisin is drawing a butterfly on squared paper. The left wing has a corner point that is 2 squares away from the vertical mirror line. How many squares from the mirror line should the matching point on the right wing be?
Answer: A. 2 squares away
In a symmetrical figure, matching points are the same distance from the mirror line. If the left point is 2 squares from the mirror line, the right point must also be 2 squares from the mirror line (but on the other side). Answer: 2 squares away.
Stuck? Start here: In a reflection, what happens to the distance from the mirror line?
This is the exact interactive worked example your child sees in SEAGReady. Step through it and watch the method build up.
Aoife is designing a logo for her school club. She wants to check if her isosceles triangle design has symmetry.
Does this isosceles triangle have a line of symmetry? If so, where is it?
isosceles triangle symmetry
Step 1 of 4
Aoife is designing a logo for her school club. She wants to check if her isosceles triangle design has symmetry.
Does this isosceles triangle have a line of symmetry? If so, where is it?
The isosceles triangle has one line of symmetry running from the top vertex straight down to the middle of the base.
The key insight: The folding test always works - if both halves match when folded, it is a line of symmetry!
Watch out: Drawing a horizontal line through the middle. A horizontal line would not create matching halves - the top and bottom of the triangle are different shapes.
These are the misconceptions we see most often in lines of symmetry, including the ones our practice questions are specifically designed to catch.
Struggling with lines of symmetry? The real gap is often in one of these earlier topics.
SEAGReady finds the exact step where your child gets stuck, teaches it with worked examples like the one above, and brings it back for review so it sticks.