CCSS Math: 4.G.A.3
Review symmetrical shapes and lines of symmetry.  Then, try some practice problems.

Line of symmetry

A line of symmetry\greenD{\text{line of symmetry}} is a line where we can fold the image and have both halves match exactly.
Example:
When we divide the figure with Line A\greenD{A}, the resulting two parts are mirror images of each other:
Line A\greenD{A} is a line of symmetry.
Want to learn more about lines of symmetry? Check out this video.

Symmetrical figures

Shapes are symmetrical\purpleC{\text{symmetrical}} if they have at least one line of symmetry\greenD{\text{line of symmetry}} on them.
Example:
This shape is symmetrical\purpleC{\text{symmetrical}}:
Because we can draw at least one line of symmetry\greenD{\text{line of symmetry}} on it:
Want to learn more about symmetrical figures? Check out this video.

Practice