The present work has the general objective to identify relativization strategies used by 8th grade students and to propose activities of language in use that help in the reflection and mastery of the Portuguese language, regarding the use of relative clauses. The relativization strategies – a variable phenomenon in Portuguese – refer to the process of structuring the adjective subordinate clauses, being an important mechanism of textual cohesion. To achieve the research objectives, we developed an interventional proposal with activities of language in use, considering three different aspects supported by the research by Vieira (2017), which addresses three axes for the teaching of grammar. This proposal can be applied in classes of the 8th year of elementary school, with the objective of: (i) proposing activities that contribute to the reflection of different strategies of relativization; (ii) promote the reflection of linguistic variation as a phenomenon inherent to any linguistic system; (iii) enable students to learn the language in use; (iv) highlighting the heterogeneity of language through different relativization strategies; (v) demonstrate the dynamic character of language and its transformations; (vii) develop the linguistic awareness of the language student/user. To reference this work, authors such as Neves (2000–2019), Cunha & Cintra (2013), Ro-cha Lima (2019), Bechara (2009), Castilho (2010), Perini (2003–2010), among others. Considering the result of the intervention proposal in which students preferentially used relative structures with low structural complexity, evidencing the lack of knowledge of the possibilities of using relative clauses, we developed a didactic proposal with language activities in use that can help students at this level of elementary school in the reflection and mastery of the Portuguese language, regarding the use of relative clauses.