Concept 5 of 6
Symmetry: Fold to Match
Today's big idea
A line of symmetry is a fold where both halves match exactly.
Fold a square down the middle and the halves match.
How it works
👀 What's going on?
Fold a shape in half. Do the two halves match?
💡 Here's the trick
A shape has a line of symmetry when one fold makes the two halves land exactly on top of each other.
Fold a square down the middle and the halves match, so that fold is a line of symmetry.
✍️ Try it
A butterfly's two wings match when you fold it down the middle. Does it have a line of symmetry? → yes.
⚠️ Watch out
The two halves must match exactly, not just look a bit alike.
Watch me solve one
Quanta solves it
“Watch how I think through one of these — then you try.”
THE PROBLEM
“A butterfly's two wings match when folded down the middle. Line of symmetry?”
- 1
Fold in your mind
Fold down the middle line.
- 2
Do the halves match?
Left wing lands on right wing exactly.
- 3
Decide
They match, so yes.
- 4
Answer ✓
yes
Now you try one — same steps, different story 👇
See it in action
⚡ Time to play!
Fold along the dashed line. Do the two halves match?
Quick check
✅ VERIFICATION
Which of these has a line of symmetry?
⚡ Finish the activity above first to answer.
Keep going!
Up next: Shape Patterns
Spot the repeating group, then continue it.