Once the size of a high-school, English class surpasses 20 students (raising a teacher class-load from 100 to 150--or more), classroom expectations and guidelines must transition from intimate, casual agreements to institutional, bureaucratic management systems.
So, much like when we interact with a large corporation rather than the owner of a small shop, students in classes larger than 20 not only get poorer service, but they respond more like members an anonymous mass confronting a bureaucracy than they do citizens of a team or a group. This dissociated anonymity negatively affects the tolerance and respect that students extend to each other and to the teacher; it negatively affects their ability to be comfortable, genuine, and honest; it negatively affects their willingness to contribute to the greater mission and to assist others, and it negatively affects their willingness to be forthcoming with contributions or requests for help. Thus, larger class sizes negatively affect both the level of individual attention each student receives and student engagement.
Perhaps class size has little effect on initial reading instruction because teachers can still offer students quality reading tools, lead meaningful discussions, and provide valuable models of good reading behaviors. However, reading assessment--the feedback that promotes learning--suffers in larger classes. When class size exceeds 20, teachers must rely much more on bubble tests than written responses. And while bubble tests have evolved tremendously, they still generally promote passive responses where students choose from a limited selection of options rather than create meaningful, active, genuine responses that demonstrate authentic improvement. Further, bubble-tests only allow students to demonstrate their abilities and learning in response to teacher-chosen passages within texts, rather than student-chosen passages--perhaps leaving much learning unobserved and unmeasured.
Increased class size also significantly affects writing instruction. Again, initially, teachers can offer high-quality materials and models, but heavier student loads mean that writing assignments must become fewer and shorter. Also, teacher feedback is more hurried and less comprehensive and precise, and feedback is returned much later after first drafts are completed. Also, perhaps the writing process must be divided into fewer steps, thus students receive less feedback throughout the process. And lastly, writing conferences--where students and teachers sit down together to discuss students’ work--often must become a thing of the past.
Because creating smaller class sizes requires increased funding, stakeholders--political leaders, school boards, and tax-paying citizens--are tempted to convince themselves (and find selective research that supports) that class size doesn't matter.
And, school administrators are in a tough spot. Surveys repeatedly demonstrate that class size is a top concern of parents, and it is likely that school administrators know that large class sizes negatively affect learning. But perhaps to appease those boards of education, political leaders, and citizens, educational administrators often promote the notion--whether they believe it or not--that class size is unimportant.
However, in terms of the students receiving personal attention, finding space as individuals within a community, and benefiting from authentic instruction and assessment, both students and teachers know full well that class-size absolutely matters.