How about some transformations ... you turn a shapeclockwise or anticlockwise around a point called the centre of rotation. The shape needs to remain the same distance from this point.

The story of Earth’s atmospheric oxygenation is one of transformation ... new perspective ties the process to changes in Earth’s rotation. This insight suggests that the length of a day ...

How about some transformations ... you turn a shapeclockwise or anticlockwise around a point called the centre of rotation. The shape needs to remain the same distance from this point.