In this chapter, we present an implementation of scientific narratives in a chemistry laboratory in secondary school; those narratives were directed to improving students’ learning outcomes in the topic of oxidation-reduction reactions. The aims of our study were: characterizing the written narratives that students produced, and categorizing different ‘types’ of narratives related to the ways in which they approached the reconstruction of the emerging scientific knowledge. As a result, we expected to identify the application of various ‘cognitive-linguistic’ skills in the narratives. Students conducted a series of school science experiments following the guide of a worksheet of standard protocols. Once the lab activity was completed, students were asked to write an interpretive text that became an integral part of their laboratory reports. Our analysis on the narratives showed that many students approached the written reconstruction of the experiments in a ‘descriptive’ way, but other modes were also present.