The masses could roll of the plane causing damage to nearby objects such as cell phones, laptops and bare feet.
A sphere, a hoop and a solid cylinder, all of the same mass are tolled down an inclined plane. Because some energy is transferred to rotational motion the object with the lowest moment of inertia wins the race. Spheres with different masses are then rolled down the plane. Both spheres arrive at the bottom at the same time demonstrating total mass does not affect the linear acceleration. Solid cylinders or hoops of different masses could also be used. This is a good demo for students to predict ahead of time what will happen as the results are not always intuitive. This demo needs friction between the rolling objects and the inclined plane to insure the objects roll rather than slide. A bag of amber such as used by gymnasts or others is provided. Should the objects start to slide rather than roll, lightly tap the surface of the plane with the bag to distribute some amber onto the plane.