Concept 3 of 8
Lines of Symmetry: Both Halves Match
Today's big idea
Fold it — do the halves match?
Matching halves = a line of symmetry.
How it works
👀 What's going on?
Fold a paper heart down the middle and the two halves land exactly on top of each other. That fold line is a line of symmetry, and only some shapes have one.
💡 Here's the trick
Look at the figures above with their dashed fold lines. A shape has a line of symmetry if folding along that line makes the two halves match perfectly. If the halves do not match, there is no line of symmetry there.
- 1.Look at the dashed line down the middle of the shape.
- 2.Imagine folding the shape along it.
- 3.If both halves land exactly on top of each other, it is a line of symmetry.
✍️ Try it
Does a square have a line of symmetry down its middle? Does a heart? Yes to both. Fold a square down the middle and the halves match; fold a heart and its two bumps match too.
⚠️ Watch out
Not every shape is symmetric. A shape like the letter F or a flag does not match when folded, so it has no line of symmetry there.
See it in action
⚡ Time to play!
A figure has a line of symmetry if folding along the red line makes both halves match.
SYMMETRY · ROUND 1 OF 3
Which figure has a line of symmetry?
Quick check
✅ VERIFICATION
Which shape has a line of symmetry down its middle?
⚡ Finish the activity above first to answer.
Keep going!
Up next: Hidden Figures
Trace it over each picture.