The aim of the study discussed in this paper was to link existing research about the argumentation skills of students to the teaching of life-cycle analysis (LCA) in order to promote an evidence-based approach to the teaching of and learning about materials used in consumer products. This case-study is part of a larger design research project that focuses on improving education for sustainable development (ESD) in chemistry teaching by means of combining a socio-scientific issue (SSI) and life-cycle analysis with inquiry-based learning. The research question was: How do students (N = 8) use scientific, ecological, socio-economical and ethical argumentation in the life-cycle analysis of a product? The research method for this study was content analysis performed on written student answers and an audio recording of a debate. The results show that the students' scientific and ecological argumentation skills with regard to the life-cycles of products were improved during the life-cycle analysis project. The studying also affected, to a lesser extent, the students' ability to form socio-economical and ethical arguments. The type of student-centred and cross-curricular product life-cycle analysis project discussed in this paper is a suitable new method for teaching socio-scientific argumentation to chemistry students at the secondary school level.