The intelligent online interactions between students and teacher are still not assured because of the fact that a learning management system could not play the role of a teacher in producing a chain of deduction. Furthermore, managing a course in existing e-learning systems has not yet guaranteed the differentiated teaching because it does not enable students to appropriately learn at their corresponding levels. In this paper, we would like to introduce a differentiated e-learning course in Vietnam. We also present some designing principles for such courses and propose some typical situations in teaching mathematics aimed at helping high school students individualize their online learning in mathematics.