SYMMETRY

Symmetry means balanced.  One side is the same as the other but may be a reflection.  Lets see if this picture helps:

When the butterfly's wings are completely open, the butterfly is balanced.  Its left half looks just like its right half.

If we draw a line down the middle of the butterfly when its wings are open we would see this:

This is called bilateral symmetry.  It means the left have and the right half are mirror images or reflections of each other.

Another kind of symmetry is called rotational symmetry.  An object has rotational symmetry if it is the same after a rotation around a center.

Here is a card which has rotational symmetry of order 2.  That means that it has two positions that look eactly like the starting position.

 

Rotated 0 degrees	Rotated 90 degrees	Rotated 180 degrees

 

If we rotate the card 90 degrees it is not the same as the start but if we rotate it 180 degrees it is the same.  This tells us that the card has rotational symmetry of order 2.  The shape below is a flower with rotational symmetry order 5.  That means that you can rotate it five times with a rotation of 72 degrees each time and it will always look the same.

flower with order 5 rotational symmetry

Do people have symmetry?  Look at this boy's face:

Which one do you like better?  What would you look like with an exactly symmetrical face?

Here's somebody with a very UN symmetrical face:






Here is a website about symmetry for you to explore.  Then we will explore angles.