A 2D symmetrical shape can be folded in half so that both sides are the same. The fold is called a line (or lines) of symmetry.
The shapes in Figure 10 have one line of symmetry.
Some shapes, such as the middle one above, will only have one line of symmetry because of the details included, like the eyes, nose and mouth. However, a circle with no added details has an infinite number of lines of symmetry!
The shapes in Figure 11 have multiple lines of symmetry.
Now try the following activity.
Activity 6: How many lines of symmetry?
Sometimes a line of symmetry is called a mirror line, because if you placed a mirror along the line the shape would look the same.
Try writing your name in capital letters and seeing how many lines of symmetry each letter has. You could use a mirror to check your answers.