Written argumentation is a complex skill to master. It can be assumed that students can transfer oral argumentation skills into a written format. Still, students from disadvantaged backgrounds for whom this task is highly novel require greater scaffolding to formulate persuasive arguments in writing. Therefore, there is a need for developing sound methodologies to introduce argumentative writing to these students. This study's objective was to address this need to develop evidence-based methodologies for teaching genre novice students at the end of primary school in Mexico (5th and 6th grades). Based on a socio-discursive interactionist approach, an introductory instructional sequence using the opinion article was designed for disadvantaged students. A quantitative pre-test-post-test design evaluated its efficacy in fifth and sixth graders (n= 50) from a rural community in northern-central Mexico by prompting an initial and final opinion article and measuring intervention changes with inferential statistics. Findings from a mixed 2x2 analysis of variance with Grade as the between-participants variable and Time as the within-participants variable suggested there was a significant instruction effect for both 5th and 6th -grade groups (main effect of Time: (F(1,48) = 28.52, p = = 0.0001, n[superscript 2 subscript p] =0.37). Students did not significantly differ by grade level (main effect of Grade: F(1,48) = 1.82, p = 0.18, n[superscript 2 subscript p] =0.03), nor did they benefit differently from the intervention (interaction of Time X Grade: (F(1,48) = 1.24, p = 0.27, n[superscript 2 subscript p] =0.02). When examining the opinion article's dimensions, the Wilcoxon signed-rank tests revealed students could improve the structure and linguistic devices, but not the communication of their texts' purpose. Results suggest a brief, socially relevant opinion article instructional sequence can facilitate the learning of argumentative writing elements in genre novice rural students.