Symmetry (particularly reflective symmetry) is when an image looks identical on both sides. Imagine placing a mirror vertically down the middle of an image, if the image looks the same in the reflection as it does without the mirror, then it is symmetrical.
Symmetry can be seen everywhere, buildings, swimming pools, drawings, just look around you, you will find at least one example of symmetry right where you are sitting (eg your chair)
Symmetry can be seen when you have balanced and equal parts on both sides of the image.
Using the alphabet, take a look at each letter separately. Which are symmetrical and which are not?
This is not true of all the letters of the alphabet however. Try the letter F. This letter is not symmetrical.
This letter is not symmetrical in any way. With symmetry, you can imagine the mirror to be in the middle of the image vertically (shown on the letter A) Horizontally (Shown on the letter F) or diagonally. If the image shown in the mirror matches the image without the mirror, then it is symmetrical.
Why don’t you try finding some symmetrical words? Such as WOW which would be symmetrical vertically or go even further with a longer word like DECIDE which would be symmetrical horizontally.
Now lets try it with something other than the alphabet. How about an insect? Take a look at this image of a butterfly. Do you think that it is symmetrical?
To check to see if something is symmetrical without the use of a mirror, simply take a pencil and a ruler and draw a line down the center, like this:
Now you can see that the image of the butterfly is symmetrical as it has balanced shapes on either side of the dotted line.
This technique can be used to test symmetry in all images. Try these out:
Which image is NOT symmetrical?