Visualizing the Avogadro Number

Background On the occasion of the redefinition of the Avogadro constant in May 2019, a brief history and some didactic reflections on its magnitude are presented. Purpose Some analogies are reviewed and others are suggested to help visualize the extent of its magnitude, and their usefulness is assessed. Design/Method These analogies are set in the teaching context of the first and second courses of the degrees in several scientific and technic disciplines. Their effectiveness is discussed for the first time on the basis of a questionnaire filled by the corresponding students. Results The suggestions for educating and learning are that the most helpful models, following the opinion of the students, are those related to more substantial items, for example, neurons, individuals, planets, above analogies on geometric constructions. Conclusions Challenging current thought, pictorial descriptions are not all the times so advantageous.