please answer this question. Thank you so much.
According to these figure, we see that while with an increase in number of student in a class, their efficiency decreases, an increase in the number of exams during the semester has a converse (is converse good in this sentence?) effect. This is because (do I have to put "that" here or not?) as the number of student lower, the teacher can pay more attention to them and assess their (status/situation) better.