This paper discusses a chemistry lesson plan on potato crisps for 10th grade (age range 15-16) chemistry classes in Germany. The lesson plan focuses on the discussion about low-fat and low-carb diets as they are presented in everyday media such as TV or newspapers in Germany. The discussion follows a socio-critical and problem-oriented approach to chemistry teaching, and is used to promote learning about carbohydrates and fats in chemistry. The goal is to foster the students' competency in reflecting upon the use of science-related information in their daily lives. The lesson plan was developed within a Participatory Action Research project. From the accompanying evaluation based on teachers' feedback, written student questionnaires, and a study based on students' group discussions, the lesson plan was found to be highly workable, motivating, and an initiator of intense discussions among pupils. These group discussions indicated that the socio-critical teaching approach has the potential to promote a more balanced and well-thought out view among some students when dealing with the aspects of healthy nutrition and various diet reports in the media. This case study indicates that the overall approach seems promising for promoting higher-order cognitive skills in the areas of reflection, and evaluating topics within the framework of science, technology and society. (Contains 1 table and 6 figures.)