Fold a paper butterfly down the middle: the two wings match! When one half is a mirror picture of the other half, the thing is symmetrical.
Key idea
Symmetrical means the two halves match like a mirror. The mirror half faces the other way.
Why it works
Many living things are close to symmetrical: butterflies, leaves, faces. When you draw one side, the other side mirrors it.
Common mistake
Many children copy the half instead of flipping it, so both halves point the same way. A mirror half faces the other way, like your left hand and your right hand.
Worked example: Let's look
Is the letter A symmetrical?
- Picture a line straight down the middle of A.
- The left slant and the right slant match like a mirror.
Answer: Yes.
For the grown-up. Fold a paper in half, paint blobs on one side, fold and press: you get a symmetrical "butterfly print." Older children can explore lines of symmetry in the Math Ladder's Lines of Symmetry.