Watch this short video on rotational symmetry.
It explains something called the order of rotational symmetry.
The order of symmetry is the number used to describe how many times a diagram will appear to be the same while rotating through 360°.
If the diagram matches up twice, it is Order 2.
If it matches the original shape three times, it is Order 3.
Order 2 = 180°
Order 4 = 90°
Order 8 = 45°
In the following diagram, what colour must go in square A for the shape to have Rotational Symmetry of Order 2.
A must be BLUE