Subatomic Particles - What's Inside an Atom?

When scientists discovered that the atom was NOT the smallest building block of matter, it took the whole world by surprise. What's inside an atom? How do we know for sure if we cannot see subatomic particles?

This video clip, from a now-rare Disney production entitled Our Friend the Atom starring Dr. Heinz Haber, takes us inside the atom and provides a short history of subatomic particles.

Although the production is from 1957, its narrative is designed to help everyone better understand this rather complicated topic.