In the context of the Anthropocene, Education for Sustainable Development (ESD) is crucial to educate the next generation. However, it has long been neglected in curricula. In this study, we were interested in knowing pupils' representations of sustainability. In this regards, 219 French-speaking Swiss pupils in compulsory school filled out an online survey. The preliminary results distinguished three groups of pupils characterised by their knowledge, attitudes and visions of the future in a sustainability perspective. Moreover, our results reveal that pupils from poorer backgrounds and in a vocational training school path were more passive towards sustainability. Finally, they understand and are practising eco-gestures, but do not understand what sustainability is. These findings legitimise the need to implement an ESD in classrooms with the aim of empowers learners with knowledge, "savoir-être" and "savoir-faire" to act for societal and environmental transformation.