Play the tape the students made in slow motion or frame by frame. Students plot on the transparency the piece of tape that marks the center of mass for the bat as they see its position on the TV screen. Do the same for the position of the ball as it crosses the screen. This could be done as a class with a few students helping with the plotting, however it is better to allow each group to plot their own segment. A weighted string hangs from the point of suspension.
Students draw the line formed by the string on the object.
Several points of suspension are chosen. Too Stand against a wall so that the heels, legs, and back are all touching the wall. Try to touch your toes so that the heels and legs are still touching the wall. Give students a few shapes, both regularly shaped and irregularly shaped. Have a dot somewhere within the shape, some shapes may have the dot at the center of mass while others should not.