Teachers and students alike report difficulties with the measurement unit called mole. This article tries to demonstrate that mole and the corresponding quantity are not exceptional. Mole lacks the context of a given amount because the unit measures the relative number of atoms compared with those present in a standard. Discusses history of…

Argues that by examining which concepts of a particular area of physics are fundamental and which are defined, teachers can choose concepts for investigation that progress logically and should minimize students' misconceptions and confusion. (Author)