Take
a look at the letter below--half of it is missing. See if you can guess
what letter it is and then click the button below it to see if you were
correct.

What
did you notice?

After
you clicked the button the right half of the letter A appeared.
It looked exactly the same as the left half! Because
the two sides of the A look the same, or mirror each other, we
say that the A has line symmetry.
We call it line symmetry because we can actually draw a line down
the middle of the A that divides the letter into two mirror images.

That
line is called the line of symmetry. We
could also fold the A on the line of symmetry and the two halves
would fit perfectly on top of each other!

Many
letters have more than one line of symmetry. The letter below has two
lines of symmetry. See if you can guess what letter it is and then click
on the button. It will show you two lines of symmetry.

Check
your understanding

Which letter
has the most lines of symmetry? Click the correct button.

The
letter H also has line symmetry, but it has another kind of symmetry as
well. Notice the yellow star on the H below. Make a note of where it begins
and watch where it ends up after you click on the button.

What
did you notice?

The
yellow star ended up on the bottom right of the H after it rotated.
Even though it was in a different place, the H still looked the
same. When a figure looks the same after it is rotated, we say
that it has rotational symmetry. The key
though is that the letter (figure) cannot rotate a full turn.
It must be less than a full turn.

The
letter W does not have rotational symmetry because it does not
look the same after it is rotated.

Does
the letter N have rotational symmetry? Make an educated guess and then
push the button to find out.