The demonstrator will take two balls, a medicine ball and a soft ball and drop them simultaneously from the same height above the floor. The two will hit the floor at the same time. Then one of the two balls will be dropped vertically at the same height as the other one which will be tossed horizontally. The question is "Which one will land first, the one that travels the least far, or the one that travels farther and faster?" It will be difficult to tell which lands first because there is too much error in the dropping and the throwing horizontally and such. It will appear one lands before the other as a rule.
How it happens
Gravity is the force that pulls both balls toward the floor. It pulls harder on the heavier ball, but the heavier ball also has a greater resistance to being speeded up toward the floor. The two effects cancel each other out, and the two objects will hit the floor at the same time, given that they are dropped from the same height and at the same time. There will be another demonstration following this which will be set up to eliminate the differences in when the balls are dropped, and the difference from the horizontal that the ball is projected.