Three metal balls roll back and forth. When rolled one way all three balls roll side by side. When rolled the other way one ball rolls ahead of the other two. Students are challenged to explain why.

A ball is rolled on a transparent surface so that the students can see that the part of the rolling ball that makes contact is not moving with respect to that surface.

This is a common toy comprised of two balls on a rigid bifilar support and revolve about an axis (see picture). When one ball collides it comes to rest sending the other off at the same speed. Other motions are also possible.

Equal time spaced or equal spaced washers are dropped. Set up for room F173 only