Rotational Symmetry of Quadrilaterals
Change the angle of rotation of the quadrilaterals by changing the slider setting. Observe the rotation of each quadrilateral and decide if it has rotational symmetry. If so, how many times does the shape match itself when you move the slider from 0 to 360?
Rotate the quadrilaterals 90. Which quadrilaterals have rotational symmetry at 90?
Rotate the quadrilaterals 180. Which quadrilaterals have rotational symmetry at 180?
Rotate the quadrilaterals 180. Which quadrilaterals have rotational symmetry at 180?
Rotate the quadrilaterals 360. Which quadrilaterals have rotational symmetry at 360?
Do you see a pattern?
Let's look at the rotations of the square
How many times did the square "match itself" in one 360 degree turn?
Rotation of Parallelograms
What other quadrilaterals had more than one match?
How many times does a parallelogram match itself in one 360 degree turn.
Rotation of non-parallelogram
A non-parallelogram only matches itself once, at 360 degrees.