To demonstrate the conservation of angular momentum.
Bicycle wheel with handles
Have a student stand on the turntable. Get the bicycle wheel spinning as fast as possible. Hand the bicycle wheel to the student. Direct the student to tilt the wheel sideways, e.g., left hand toward the floor. As he does so, the student will begin to rotate. Tilting the other direction will cause a rotation in the other direction.
Using a low I person will may the effect more dramatic.
After the wheel has been tilted, the angular momentum of the wheel is of the same magnitude but now in
a different direction. It now consists of a horizontal component as well as a component directed downwards.
To conserve angular momentum, the system rotates in such a way as to add an upward component to cancel the
downward component from the wheel. This leaves a small amount of horizontal angular momentum that is sunk
into the Earth.