This paper proposes a theoretical approach to discuss the relations among reality, chemists’ interactions with it, and the resulting interpretation and representation of the acquired scientific knowledge. Taking into account that such relations are of semiotic nature, this paper aims at discussing in the light of Peirce’s theory of signs different descriptions of chemical activity and chemical education proposed by Alex Johnstone and elaborated by other science educators. In order to discuss the contributions and limitations of the proposed theoretical framework, (...) and considering its potential interest for chemical education, an example on the communication strategies for the content ‘vapour pressure’ found in twentieth-century general chemistry university textbooks is also presented. (shrink)