What's a line of symmetry? Symmetry in maths means that an imaginary line can be drawn down a shape so that you can fold the image and have both halves match exactly.
Look at this picture of a house, you can see that if we were to draw the exact mirror image on the blank side of the page, we'd have a beautifully drawn house!
You may want to think of symmetry as two things being exactly the same after a fold. We think to really get to grips with symmetry it's always worth trying it out with some paper, so you can put it into practice!
The other thing that you can do to help you grasp this is to use a mirror. If you placed a mirror on its edge on the dotted line of the letter U below, and then looked in the mirror... guess what? You'd see the whole letter U again! Can you think of any other letters of the alphabet that may be symmetrical?
Some shapes may have more than one line of symmetry. If we look at the letter U above we can see that we can only fold this letter in one place for it two be identical on both sides of the fold. But what about the letter H below?
We'd say that this letter has two lines of symmetry. Can you see? There are two places where we could fold this shape to get a mirror image.
In this activity, you must decide whether the given road signs have a line symmetry or not and how many lines of symmetry you can see. Remember this just means that a line can be drawn down them and you would see both halves being a mirror image of one another!