In the following sentence, I want to express that in smaller classes, teachers are able to pay more attention to the individual level of knowledge that each student brings to the classroom when they first start the course.
There are more opportunities to adjust to differences in ... .
I have "entry level" in mind, but I think that's often used in an entirely different context (i.e. to describe the level of the course itself). "Beginning level" and "starting level" are other possibilities, but they sound a little odd to me. I also don't mean starting competencies, because that is more often used in the context of a requirement and that is not what I want to express here.