Mystery boxes

This week we started atomic theory and history. Part of the lesson is the meta idea of science, how do we know what we know? We can not look inside an atom, so how do we know what the structure is? We do a mystery box activity where the students use the 'thunk thunk' they hear to infer that their box (atom) contains two objects. I don't tell them the 'right' answer, instead we rely on the scientific community to come to consensus, hence the comparative drawings on the board at the end of the day today.