This paper presents a method for involving learners in awareness-raising and real changes in consumption. The described method is a teaching assignment comprising a self-audit of household chemicals consumption, system thinking to find the main causes and consequences, finding solutions and taking action. Findings about students household chemicals consumption patterns and their reactions one month and six months after the assignment are presented and analysed. We found that the students households use considerable amounts of chemicals and in most cases do not pay attention to their health and environmental impacts when making purchasing decisions. When doing this, students were able to find good alternatives to reduce the environmental impact of their household maintenance and have changed their behaviour six months after the assignment.