Teaching English in large classes is a trend that has not changed in the short term at many universities in Vietnam in general and at Electric Power University in particular, which causes low efficiency in teaching. Class size of 40 to 50 students is too large, leading to three common problems for teachers including physical, psychology and pedagogy. In reality, given time restrain in class, large class and great variety of students serve as impediment for learning outcomes of high quality. Therefore, the employment of proper pedagogical approaches, appropriate teaching strategies would be an optimum solution to the conundrum.