Page 1 of 1
Hands-on
Activity
GOAL
MATERIALS
Investigate line and
rotational symmetry.
• tape
• paper
Investigating Symmetry
A figure has line symmetry if you can fold it into two halves that are mirror
images. A figure has rotational symmetry if you can turn it 180 or less about
a fixed point so that it matches up with itself again. You can fold and turn
paper to investigate symmetry in a rectangle.
Explore 1
Determine whether a rectangle has line symmetry.
1
Fold a rectangular piece of paper horizontally.
2
Open the paper and fold it vertically. Notice that
both the horizontal and vertical folds produce
two mirror images.
3
Now fold the paper along its diagonals. Notice
that for each of these folds the two halves are not
mirror images. Experiment with other folds. You
will find that a rectangle has only 2 lines of symmetry.
Explore 2
Determine whether a rectangle has rotational symmetry.
1
Tape a rectangular piece of paper down on your desk. Place a second
piece of paper over the first so that they match up.
2
Place the tip of your pencil on the center of the top piece of paper. Slowly
turn the top piece of paper clockwise. Notice that the pieces of paper match
up again after a turn of 180, so the rectangle has 180 rotational symmetry.
1. Determine the line symmetry and rotational symmetry of a square.
Explain your reasoning.
2. Critical Thinking Draw a triangle that has three lines of symmetry.
510
Chapter 10
Geometric Figures