This compact collection of slides explains the history and use of the mole unit. Relative atomic mass, as John Dalton understood it, is explained. Avogadro's number is also introduced. The mole, or the unit for the amount of a substance, is explained. There is a lot of text on most of the slides. It is recommended that you spread the material out over a few more slides to make it easier to read before employing in your chemistry class.