This study investigates how teaching can support students' ability to apply rock identification by addressing scientific observation. In the context of geology education in Norway, we investigate two cases in which different approaches to teaching rock identification are carried out. Case A involves traditional teaching activities in one class of upper secondary school students, while Case B consists of teaching activities focusing on observation in a class of elementary school students. The study relies on analysis of video data using headcams from classroom activities and fieldwork. A year later, we asked the same students to apply rock identification to samples that were new to them. Results indicate that the teaching approach influenced the students' opportunities for developing an understanding of rock identification. The students in case A identified the samples by applying specific names of rocks and geological terminology, which led to errors and misconnections. Their application of rock identification can be characterized as "name-dropping." By contrast, the students in case B identified rocks by noticing the patterns. They also explained theories of rock formation and geological terminology, thus demonstrating "understanding." We discuss how the findings from case B can be translated into a tool for teaching rock identification.