A line of symmetry is an imaginary line on a shape such that the shape can be folded along the line into two matching parts. Another way to think of it is an imaginary line on a shape that divides it into two perfect halves, each the reflection of the other.
Generally, students have little trouble deciding if a figure has one or more lines of symmetry. If students get stuck, we cut out the shape and physically try to fold it. Here are a few tricky ones:
Another tricky factor is knowing HOW MANY lines of symmetry a shape can have. This can be a surprising number. However, there is a trick. An octagon has eight sides, eight angles... and eight lines of symmetry. A hexagon has six sides, six angles, and six lines of symmetry. Any REGULAR POLYGON has the same number of sides, angles, and lines of symmetry.