Observe the clock face and talk about how much rotation is required.

Two-dimensional rotation will keep a fixed point on the clock face. That's the end of the pointer and the center of the clock face.

At the same time, the compound of rotation is still rotation. For example, a rotation of 10 degree is a rotation, then another rotation of 10 degree is still a rotation, and the two add up to a rotation of 20 degrees.

Of course, the length of the pointer is constant when it rotates. This is called the distance-keeping characteristic of rotation.