Based on the triangle mentioned by Johnstone (1991, above), there are three domains in chemistry that are
related to each other. These are the macroscopic domain, which is tangible, edible and visible; the microscopic
domain, which includes the molecular, atomic and kinetic parts; and lastly symbolic or representational chemistry,
including the use of symbols, equations, stoichiometry and mathematics. Because of this complexity in the nature of
chemistry knowledge, students find it hard to study all three levels at the same time. Research has revealed that the
part of chemistry which students find most difficult to learn is the sub-microscopic level and many scientific
misconceptions have arisen regarding this level (Nakhleh, 1993; Garnett and Hacking, 1995). Therefore, Reid and
Yang (2002) propose that teachers should help students to understand the macro-micro-symbol triangle and avoid
rote knowledge.