Over the past years, differentiated instruction has been proved to result in effective language teaching (Harmer, 2012). However, differentiation has never been easy, especially when teachers have to teach large classes, let alone large English classes. For effective differentiation, teachers need to allocate lots of time and energy to plan for their lessons to satisfy students' of different needs. Besides, challenges are numerous when teachers of English teach large classes in areas with poor resources (Shamim et. al., 2010). In addition, in these classes students are of mixed-ability, learning styles, levels of language proficiency, cognitive ability and so on. Nevertheless, opportunities are also available for teachers who work with large groups of students when teachers can exploit these students' resources. This presentation aims to (1)clarify the challenges facing teachers who teach large English classes; (2)outline possible opportunities to teach large English classes effectively through using appropriate differentiated instructions, and (3)highlight a number of practical activities that can be used in large classes to increase students' interaction and collaboration in both offline and online learning environments. Keywords: differentiated instruction, large class management References Harmer, J. (2012). Essential Teacher Knowledge. Pearson. Renaud, S., Tannenbaum, E, & Stantial, P. (2007). Student-Centered Teaching in Large Classes with Limited Resources. English Teaching Forum. No3. Shamim, F. et.al. (2010). Maximizing learning in large classes. British Council. Ur, P. (2012). A Course in English Language Teaching. Cambridge University Press.