Learning Takeaways: After this lesson, students will be able to:
A figure is symmetrical if it can be split exactly in half. Look at the example below.
Symmetry means that both sides are the exact same when split in half. 

Notice that both sides of the happy face look exactly the same. That means this figure is symmetrical. 
Look at the next example. Is this figure symmetrical? Does it look exactly the same on both sides of the line?
This octagon has more than 1 line of symmetry. Can you find the others? 
The octagon is symmetrical. If you fold it where the line is, each side would match perfectly. But how do you know when a figure is NOT symmetrical? Look at the example below. This figure is not symmetrical. Can you figure out why?
Both sides are not the same! 
The lightning bolt is not symmetrical because it does not split in half with two equal sides. One simple way to see if a figure is symmetrical is to draw it on paper and fold it in half. If the sides match completely, it is symmetrical.
A line of symmetry divides a figure in half. Figures can have more than one line of symmetry.
Look at the square below. How many lines of symmetry do you count? Be careful to count each line only once!
Does a rectangle have as many lines of symmetry as a square? Remember that a line of symmetry will split a figure in half so that each piece is exactly the same. Notice that the rectangle has two fewer lines of symmetry. Can you think of which direction the line of symmetry cannot go?
A rectangle cannot have a diagonal line of symmetry like a square because the sides are not the same length. If you fold this rectangle diagonally so that Corner A meets Corner D, the sides would not match. Try it with a piece of notebook paper!
You can draw lines of symmetry


Figure A is the original drawing and figure B was drawn to be a symmetrical or identical part. 
Here is a list of activities that you can do at home or in your neighborhood to help understand symmetry.