Studies from many countries report that secondary school students do not master written argumentation well enough. This article presents a case study from lower secondary school where the question of problems in written argumentation is approached from a different angle: instead of focusing on argumentative weaknesses in student texts, it concentrates on what students are capable of and struggle with when they write argumentative texts in cooperation with a scaffolding teacher. Findings from this study show that a clear text pattern (...) communicated through teaching and teacher response helped weak as well as strong writers to improve common problems related to audience awareness and the structure of argumentative texts. In cooperation with a commenting teacher all students were also able to support a standpoint with more reasons and to strengthen their own position by refuting a counterargument, although to varying degrees. However, only a couple of revised texts suggest that students had the will, skill and insight needed to follow up teacher response that encouraged a more distanced view on heated debates, conflict negotiations, self-reflection and critical thinking. (shrink)