📐 Symmetry
Symmetry means an object looks exactly the same on both sides of a separating fold line
▶ Play Door 17Symmetry
Have you ever folded a paper heart or looked closely at a butterfly's wings? If you can fold a shape perfectly in half so that both sides match exactly, that shape is symmetrical. Symmetry is all about balance, matching, and mirror images!
• What is a Line of Symmetry? A line of symmetry is an imaginary straight "fold line" that cuts a shape exactly in half. If you place a mirror right along this line, the reflection looks exactly like the other half of the shape.
• Vertical Line of Symmetry: A straight line going up and down (|).
• Horizontal Line of Symmetry: A straight line going sideways (
Worked example
Problem: Look at the standard Rectangle shown below. How many different lines of symmetry can you find? ``ascii ┌───────────────┐ │ │ └───────────────┘ ``
- Try folding the rectangle vertically (up-and-down) down the middle. The left half matches the right half perfectly. That is 1 vertical line.
- Try folding it horizontally (sideways) across the middle. The top half matches the bottom half perfectly. That is 1 horizontal line.
- Try folding it diagonally from corner to corner. In a rectangle, the corners do not line up perfectly when folded diagonally (try this with a piece of paper!). So, diagonal folds are not lines of symmetry.
- Add up the correct lines: 1 + 1 = 2.
Answer: 2 lines of symmetry