School subjects can provide a good context for learning a second language. This is especially true for science as it can involve a range of student centred activities, which involve students in collaborative communication related to a range of different competences. This paper reflects on one approach to learning in a second language, using the approach promoted by the PROFILES project. It illustrates how the PROFILES approach can realise greater potential for student language development, focusing on learning about carbon dioxide in an inquiry learning format, permitting experimentation and interpretation of the outcomes. The approach is via a scenario providing a familiar setting for the learning and, following experimentation, the approach moves to decision making where the focus of carbon dioxide is on being a greenhouse gas and effecting global warming, this leading to a debate on acceptable levels of carbon dioxide and the effect of deforestation. The latter involves the use of argumentation skills in a socio-scientific setting allowing the utilisation of a second language in a different dimension to that of providing scientific explanations.