[R. Scott]

When I studied physics in high school there were only three elementary particles – the electron, proton and neutron. There was wild speculation that these might be made of other simpler particles, but many doubted it.
Was it really that long ago?

[AdmSmith]

Perhaps they only talked about these three particles. The positron was discovered in 1932 by Anderson, http://www.nobel.se/physics/laureates/1936/index.html but it did not materialize in high school until much later.