Recognize that the model of matter that we use during this unit is essentially that proposed by Democritus.
Students watched a 2 minute video on the first recorded idea of ‘small particles so small they could not be broken down into anything smaller’.  Our current model of the particle is similar to the 25 century old first proposed by Democritus, who said that the world consists of matter and void.  He thought that if we broke something (a rock) in half, and continued to break each half into another half, etc, that it would reach a point in which it could not be broken down anymore.  He called this particle the atom.