We experimented with teaching nanotechnology in high school within the perspective of citizenship education in science by involving experts in nanotechnology, education, ethics and philosophy. After training, the students debated a Socially Acute Question (SAQ) that they elaborated during the various phases of instruction. The field of SAQs represents a French orientation for the teaching of SocioScientific Issues. We analyzed the interactions of students in the debate to determine their risk perception on nanotechnology. We compared and put their arguments into perspective using various analytical frameworks. We observed two contrasting argumentative tendencies: one reflecting a positivist view that involved an individualistic use of nanotechnology and science and one carrying a critical and humanistic vision of the use of nanotechnology and science.