What's the "Atom Board?"

I had someone email me this question and (as all teachers know) one question means others have the same question.

The Atom Board is a CPO Science manipulative. (Picture and explanation from CPO here.) It's on my worksheet because when I wrote it my school had the all of the CPO gear.

This year I am at a school that doesn't have the CPO atom boards, so I am having to improvize. My thinking right now is to hand out a picture of the atom with area for the nucleus and orbitals. Instead of marbles, I am going to use either flat washers, beans...- something that will represent the subatomic particles.

The important part of this is that the students have a hands-on manipulative that requires them to put the protons and neutrons in the nucleus and electrons in the orbitals, filling up the lower levels first. Other things they should be able to do: find the number of neutrons given the mass number and element (mass number - protons = neutrons).

TESTS: A wonderful lab practical for a test. Require that they make an atom correctly during their test. Have a few boxes ready with the atom manipulative inside it, so others can't see them and "cheat".