This study investigates teachers’ defining differentiated instruction, their perspectives, their practices, and the factors behind these practices. Thus, findings are expected to be the voices of teachers in practicing differentiated instruction. This research is designed as a qualitative study consisting of 537 teachers. Structured open-ended questions were used to collect the data via e-mail. Content analysis was applied to analyse the data. As a conclusion, the majority of teachers perceive differentiated instruction in its true form, that is, addressing the diverse needs and interests of students; differentiating the context, material, activities and process. Most of them from both public and private schools stated that the implementation of differentiated instruction made students happy and supported permanent, meaningful learning. However, it was found out that teachers mostly do not implement differentiated instruction in their lessons. Some teachers couldn’t practice it because they do not know what it is, most of the teachers stated that because of the central exam pressure, lack of material and class size, they cannot practice it. As for the teachers who can practice the differentiated instruction in their classes, they emphasized that it has a positive effect on the student, they know and implement the method; the school implements an education model based on differentiation.