This study focuses on students' experiences, aged 15-16 years old, with four visual representations (VRep) of science school textbooks, all related to microcosm. The textbook units, in which these VRep are included, had been taught long ago, while these particular VRep were presented to students without any captions or other type of relevant explanations. They were asked to provide their own labels that according to their own opinion would better describe each VRep. Findings reveal the low degree of students' familiarization with the teaching material and their difficulty to recognize already known entities and concepts presented. The most recognizable VRep is the one of DNA, as its prototype model seems to be labeled most accurately. The analysis of students' descriptions has lead to a scheme of categories that reveal different levels of students' awareness and discernment of the content of the VRep. The findings are also discussed in terms of the role and effectiveness of teaching materials in the science classrooms.