Abstract
It is not easy for secondary school learners to comprehend the concept of chemical equilibrium at the level of understanding. In this context, a feedback is important for the teachers to optimize their help to students in constructing this concept. We designed and tested sets of particularly prepared tasks, the solution of which reflects the depth of understanding of the basic concept in macroscopic, submicroscopic and symbolic representation. Difficulties in understanding the chemical phenomena and concepts do not result only from the existence of these three levels or from their explanation using abstract concepts, but also from the lack of interconnection between these representations. Consistent interconnection of these levels can lead to an internal conflict in students, and consequently to a more profound understanding of the concept or relationships between concepts at multiple levels of representation to understand them or to change the meaning of one to another. There is also a close connection with the aspect of memory, algorithmic and conceptual approaches to solving educational situations, which extends dimensionally and reinforces the need for a more comprehensive grasp of learners’ mastery of the given concept. The teacher cannot expect that the learners without intensive training, e.g., only by observing the macroscopic representation, can interpret the essence of the submicroscopic representation. Therefore, these aspects need to be consistently involved in the model of learners’ cognitive process early enough to apply them in the educational practice without any problems.