The present protocol describes the background, theoretical framework and methods for a qualitative study of co-taught, Norwegian, L1 classrooms-The Seaside case. The participants are six classes and their teachers from six different schools in the Seaside municipality. All classes had one extra teacher in all 8 L1 Norwegian lessons each week, in Year One and Year Two. Co-teaching provides pedagogic potential and flexibility and can enhance students' learning. However, evidence from teacher-student ratio research is inconsistent across contexts (Solheim et al., 2017; Solheim & Opheim, 2018), and there is also a need for studies exploring connections specifically in the Norwegian school context. Our overarching research questions are: (1) What characterizes literacy practices in L1 initial co-taught literacy lessons? (2) How is the extra teacher resource utilized in L1 initial co-taught literacy lessons, and what characterizes interaction, patterns of discourse, organization and roles in the classroom (teachers and students)? (3) What are the students' conditions for participation, engagement and dialogue in L1 initial co-taught literacy lessons?