Nastassia, Class size matters, and I am not sure there are any consistencies in how to approach a large class or smaller class. Most of the time it comes down to how well a particular group of students have prepared, their prior knowledge, and factors that affect their ability to study (free from interference of work, childcare, travel, illness, etc). For instance, you point out the importance of good math skills for students taking chemistry. I agree, and this is a good example if a student is weak in math, more instructional time will be spent due to that weaker skill level. Barry Westling