This study clarifies whether secondary school students develop their argumentation skills through reading and collaboration. The students first constructed an individual argument diagram on genetically modified organisms, read three articles, and improved their diagrams. Next, they engaged in a chat debate, reflected on their debate by constructing a collaborative argument diagram on it, and finally finished their individual diagrams. The analyses compared the diagrams students finished after the debate and reflection with the diagrams they constructed before the debate. Collaboration not only encouraged students to elaborate their previous arguments but also helped them to recall and create ideas and arguments. (Contains 1 table and 5 figures.)