Can you balance a pencil on it's point?  We didn't think so until we learned that we could add counterweights at the bottom to make it balance and be in a stable position.  We used clothespins as counterweights to add mass.  We learned it is important to add the counterweights at the bottom.  A low center of gravity helps things balance.  We learned that gravity is a force that pulls things down, but if you put the counterweights at the bottom it will stay straight or weeble and wobble, but it won't fall down. We learned that mass should be equally distributed around the center of gravity for things to balance.