We report from the first iteration of a teaching sequence on nanoscience and nanotechnology (NST) in a Swedish secondary school science classroom. Twelve students, age 18, had seven lessons based on design principles of student ownership and talk space in the learning process. The study covers three areas: 1) the students’ learning of basic knowledge of NST, 2) their risk understanding of NST and 3) their ability to discuss NST as a socioscientific issue during a debate. The present paper focusses on a video recorded and transcribed final debate. In this debate students discussed NST as a socioscientific issue, identified risks and benefits in six different NST areas. These areas were selected from an online outreach activity and studied in groups of two. The debate showed that it is possible with only small resources and few lessons to introduce a discussion promoting climate in the classroom and that students can engage in qualified argumentation on NST. To further develop these aspects, we will add a lesson before the debate providing the students with tools for risk assessment and argumentation in coming iterations of this teaching sequence. Our analysis categorized the students into four groups by argument and decisive values indicating different degrees of risk averseness. These four groups share similarities with the argument–decisions found in earlier science education research. We conclude that students’ judgementof risks and benefits are based on knowledge from the studied course material, but that the decision made also includes personal values. In our continued research with this NST teaching sequence, we hope to find out if all these four groups could be found within each NST area which would indicate that these are general attitudes towards NST risks.