This study is based on the presumption that language is fundamental to the construction of knowledge. In addition, linguistic demands are incorporated in the policy documents of the upper secondary edu­cation of Sweden; students shall, during their education, be given the opportunity to appropriate certain linguistic tools. The purpose of this thesis is to investigate how teachers and students in upper secondary education manage and utilize the discourse of social science in both speech and writing. More specifically, two classes are studied during three terms. The teachers’ ability to organize and support the students vocally and in written is examined, so are the effects of the teaching on students’ writing. The origin of the study is constituted by a sociocultural stance provided by Vygotskij, Bakhtin and Halliday. A combination of a functional perspective on language and a cognitive is probed, where the study is comparative in nature consisting of an experimental class and a control class. The importance of language for the creation of knowledge has been communicated to the teachers of the experimen­tal class, with provided complementary subject didactic literature. This literature offers support for teachers to augment the use of explicit teaching and enhance student awareness of how conceptual structures mould social science. Qualitative analyses are performed on the basis of teacher-student dialogue and written tasks by a group of selected students. The ana­lytical tools object language – metalanguage, linguistic operations and knowledge structures are developed for the purpose of processing data, and have been combined with the tools activity analysis, subject-related concepts and text activity. The results from the analyses display no difference in the handling of the discourse of social science between the experimental class and the control class. The teachers of the experimental class, like the teacher of the control class, are primarily utilizing object language where knowledge structures are visible, as opposed to a combination of object language – metalanguage. Furthermore, they exhibit diminutive use of dialogue in their teaching. The students of both classes, on their hand, demon­strate an equal progress in textual development. This study concludes that the experimental class has not been provided with sufficiently explicit support to advance in the struc­turing of knowledge and in level of reasoning. A more efficient support to teachers to manage these analytical tools would, in all probability, give them, and through this the students, an increasingly profound insight into structuring of text activities, the meaning and signalling of linguistic operations, the construction of subject-related concepts and, most importantly, how these three tools are interrelated.