An instructional approach is presented for teaching the mole concept to high school introductory-level chemistry classes. Extensions to the strategy are presented for more advanced classes. The strength of the approach is based upon discovery. Students discover the Avogadro number and the mole concept. The discovery is based upon calculations that are similar to that used by the International Avogadro Coordination (IAC) in determining the Avogadro constant. Students in advanced classes use data from the IAC to calculate the most precise and accurate values for the Avogadro constant.