Hello, I'm Mr Firth, and together we're going to learn about lines of symmetry. Symmetry is when one side of a shape looks exactly like the other—just flipped. Lots of buildings use symmetry because ...

We are fond of saying things are symmetric, but what does that really mean? Intuitively we have a sense of symmetry as a kind of mirroring. Suppose we draw a vertical line through the middle of a ...