Lesson 1 of 9
Fold it, and it matches
Show on a big screenWet paint is dropped on one half of a page. Fold the page shut. Then open it. Two matching paint patches show, one on each side.
Step 1 of 3
- A house shape, with a fold line down the middle.
- Fold along the line. The shape lands on itself.
- Every corner lands on a corner. It matches exactly.
The rule
The fold leaves a crease, a line in the paper. That crease is a line of symmetry. Fold along it, and one half lands exactly on the other. Not close. Exact. Lands means comes to rest on top. A shape with such a line has symmetry.
Flipping every point straight across the line is called a reflection.
Rangoli and kolam are floor patterns on a dot grid. Draw one half. Reflect it.
Tap a square in the lab. The mirror paints its matching square on the other side. Switch the mirror off to see squares with no match.
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Try the lab to finish this lesson.