It is not Easy to do Simple Movements!
To have fun with centre of mass
Sit on chair with legs and backbone vertical. Try to stand up without moving the upper portion of your body forward or lower portion of your body backward. Can be used to explain concepts like centre of mass, torque etc.
Variant: Turn your right side to the wall. Touch your right leg and cheek to the wall. Now try to raise your left leg away from the wall.
Both of these stunts require you to shift your center of gravity away from the support base. The body maintains balance with little adjustments so automatically that we never think about them.