The aim of this personal reflection is to revisit the major concepts that have informed my academic research in the area of applied linguistics and second language development, and show how my overall pedagogical approach has evolved, thanks to the contribution of Vygotsky's sociocultural theory (SCT). The main focus of this paper is on the phenomenon of language variation in English-as-a-lingua-franca (ELF) contexts, and especially its impact on the English of the classroom. In particular, I will consider the importance of embracing diversity in ELF, by adopting a post-normative response to learners' use of English, and explain how SCT and ELF studies may converge. For instance, this is possible when students are involved in authentic communication tasks, through web-mediated telecollaboration projects. I will conclude this paper by saying that approaching language variability with an open mind is necessary if we believe that ELT should be connected to the world outside the classroom and to the process of change that English is undergoing nowadays.