Nowadays, teachers must deal, as never before, with diversity in classrooms. Differentiation practices help teachers to address this diversity in an inclusive setting. However, teachers' perceptions about classroom heterogeneity are fundamental to examine whether they are competent to screen their pupils' needs. The present study used a qualitative research design in order to understand how four teachers who teach the same classroom of a secondary school recognise and address those diverse educational needs within a classroom. Results showed a distinct view of students' diversity within a classroom. Moreover, differentiation strategies to respond to this perceived diversity were only partially used. [Paper presented at the Inclusive and Supportive Education IV Conference Congresso Internacional da Pró-Inclusão (8th, Lisbon, Portugal, July 26-29, 2016).]