this question recognizes that students are different even when they are taught by same teacher, the difference comes about due to various disparities of IQ, environmental make-up, biological, historical, etc
Different students perform differently, even though they have the same teacher. There are always high as well as low performers. In order to catch up with the high performers, the low ones need to work harder. Naturally, they need more attention, encouragement and assistance. This is where we, as teachers, are needed the most. We definitely have active role in closing the gap between the low and the high performers. On most occasion, all those low performers need is just a pat on their back.
if they have different environment, historical background any other difference, we have to focus they are the students has one group and we have to concentrate and differentiate poor, medium and well understanding students. then our focus more with poor and medium students and give assignment to well understanding student to discuss with poor students about learning style comparing to us their age group people discussion absorbed by students and should some appreciation for all, then the class will be more active