Schools are often encouraged to facilitate extra-curricular learning within their own premises. This study addresses the potential of social networking sites (SNS) for supporting such out-of-class study. Given concerns that learning on these sites may happen at a surface level, we adopted self-determination theory for designing a social networking experience that aspired to offer a "community of inquiry". A case study of a Mandarin class is reported, in which seven children voluntarily attended afterschool lessons and used a SNS for 12 weeks. Pedagogical strategies to create a sense of relatedness and competence and to offer autonomy support were used in order to steer their informal communication and exploration towards deep and meaningful learning. Our findings show that the online social networking activities are not used simply to extend formal lessons to informal online environment, instead they open up opportunities for students to benefit from informal exploration and thus enrich their experience of learning about the subject.