Does class size really matter?

Class size is frequently a topic for discussion by administrators and teachers. Even when we end up in a school that has lower class size averages compared to other schools, the class size issue does not always appear to go away; we perhaps do not recognize it when conditions are good.

So, why is there such a debate over class size? Firstly, student numbers in classes are perceived to be directly proportional to teacher workload. Secondly, it is claimed that when class sizes are too big teachers cannot give the same individual attention and feedback to students than if there were smaller classes. Subsequently, there is the call for smaller class sizes because this would improve teaching and learning.

Logically speaking, this makes sense but if class sizes were lowered would there be a difference in student learning and achievement outcomes? Not necessarily so, and here’s why.

John Hattie undertook a meta-analysis of factors that influence student achievement. The aim of the study was to analyze as much research as possible to rank the practices that have the biggest effect on student achievement. While his work has been criticized in some corners, we can still draw a lot from it and it is a great starting point for reflecting on what we need to do in our schools to improve student learning.

Having heard Hattie speak some years ago, he upset quite a few of my colleagues when he said that class size does not have much impact on student achievement. Of all the interventions that we could put in place to positively influence student achievement, class size had little impact when compared to other strategies. This is not what teachers wanted to hear at all. Unfortunately, policymakers also misinterpreted Hattie’s research to justify increases in class size or no reduction.

If all schools were to reduce class sizes tomorrow, while pleasing some teachers in terms of their perceived workload it could possibly have little impact on student learning for the following reasons:

  1. If professional practice is poor, the number of students in a classroom may not matter too much, as the teacher is likely to struggle and get mediocre outcomes with 15 students just as much as working with 20. Therefore, a student would be better off having a good teacher in a large class than a poor teacher in a small class.
  2. When class sizes are lower, some teachers do not modify instruction accordingly. Many of the methods used with large class sizes are not always effective with smaller groups.
  3. When it comes to individual feedback, sure, smaller class sizes would help the teacher spend more time with each individual. This, however, relies on the assumption that with small class sizes, the teacher will give more time to feedback. Even then, how do we know if the feedback is actually going to be effective?

Taking a closer examination of the contact hours teachers have with their classes as being more significant in improving student learning may actually be a better way to go than reducing class size. If teachers actually had less contact time / less classes then they can spend more time with collaborative work and professional learning that improves classroom practice. Obviously, this is difficult to do also, owing to the budgets given to schools for staffing.

In essence, if class sizes do not get reduced, there are plenty of ways we can improve, as teachers and schools, to work with the numbers. This post does not mean that class size is not important but without effective teaching it does not make much difference other than to personal workload in terms of marking and, possibly, teacher classroom management. Yes, most teachers do work very hard, administrators work hard too, but we always must ask ourselves the question, as reflective educators, are we working as smart as we work hard?

Originally posted on

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  1. Good bit, Richard.

    A few reactions, though. First, I think it’s interesting that all of the reasons listed that reducing class sizes has little impact on student achievement are based on the assumption that teachers stink anyway — so if a teacher is going to stink, let them stink with 45 kids. Why reduce class sizes — and assume the expense that goes with that change — only to have bad teachers in classrooms with fewer kids?


    And I think there’s a “chicken/egg” scenario going on here. Maybe ineffective teachers are ineffective BECAUSE their workload is ridiculous? Maybe if teachers had a lighter load — as you mentioned in your argument to reduce contact hours — we could invest that time in developing better practice.

    This stuff is all on my mind this year because for the first time in close to 15 years, I have classes that are under 30 students. In fact, my biggest class is 26 kids — and my whole student load is 88 kids. Typically I’m up near 120-130 kids.

    And I can tell you that I’ve already invested FAR more time into planning and reflecting and revising my practice than I have in previous years mostly because the management workload is lighter. When I can grade papers and enter scores in less time, I’ve got more time to turn around and think about the work that I’m doing in my classroom.

    I also find myself tinkering with my practice — taking professional risks — more often this year because I’m taking those risks with smaller classes. Trying something new in a room of 22 is a lot different than trying something new in a room of 36.

    My push against arguments like “reduce class size OR give teachers fewer contact hours” is that if we REALLY want teachers to innovate and reflect and give feedback and change practice and collaborate, we would do BOTH of those things!

    Does that make sense?

    Thanks for making me think this morning…

    August 29, 2015
    • Thanks for your thoughts on this Bill. I feel very much caught in a catch 22 situation. I get frustrated when some teachers use class size as an excuse not to change practice. Yet at the same time, I really feel for those who are making every effort to reflect on what they do and improve their practice. Which is why reducing class size for some teachers may make a significant difference.

      I believe strongly that with most issues in education, if we can improve teacher practice we can address most of the problems to a certain extent. Though, I cannot help thinking that our best teachers are being taken advantage of by policymakers and the fact that teaching is more than a job – we make a difference to young people and they rely on us to support them. For this reasons, we should still fight the fight with policymakers but perhaps the wrong battle is being fought. I think reducing teacher contact hours would be far more productive than reducing class size because of the support that can be given plus the collaboration that could take place such as peer observation.

      I am fortunate to work in a school where class sizes are small in comparison to where you work. This is not always appreciated by some of those fortunate to work in the school who see problems as always Admin’s issue rather than reflecting on what they can personally do to make a difference.

      Once again, thanks for giving this your thought and taking the time to contribute to the discussion.

      All the very best.

      August 29, 2015
      • Carlos Moreno said:

        As an English Department Chair at one of the highest performing schools in California I am deeply offended by Hattie so called research and Mr. Burton’s article about class sizes essentially not meaning much. At the moment I have 172 students. My largest class is 41 (Freshmen Honors) and my smallest class i loaded at 32. The work load has become so great recently that I basically have eliminated entire assignments and lessons because there simply is not enough time for the grading. I also have ceased making comments on student essays relying more on holistic rubric scores. I also have stopped calling all parents simply for an introduction. If fact so much of my time is absorbed in the clerical work and grading involved in maintaining that many students that I simply don’t have time to do many of the strategies and interventions I used to do. This mind you is with me putting in over 50 hours a week in this job. Unfortunately I have seen a real decline in student work, achievement and an increase in the amount of students that fall through the cracks. I have personally seen this because when I began teaching 11 years ago we still had the 20 to 1 in a freshmen class. At that time my case load was in the low hundreds or sometimes even in the 90’s. The amount of time I was able to spend with both students and parents was irreplaceable and nobody fell through the cracks unless they themselves jumped through one purposely. I find it irritating when so called education researchers conduct a bit of data, observe a few controlled classrooms and come up with a theory to sell a book. Most if not all of these researchers have never spent any significant time in public high schools dealing with what teachers who are in the trenches deal with on a day to day basis. This is the equivalent of the College Boy Officers sent to command men who have been on the front lines for months or even years. Their message simply does not ring true because there is no SUBSTANCE behind it. And please don’t bore me as Hattie’s research does with references to “Figure 4.1” and “Table A”… Bottom line: none of this means anything when faced with the real challenge of teaching teenagers many of whom do not want to be there as they are exposed to a subject they care little about. In addition the idea of less contact time is “nice” but at the moment nothing more. Since I have no more room in my class to place any more seats (I have 41 desks) the district would have to fund the construction of lecture halls and auditorium sized classrooms since the current ones would simply be too small. I don’t think I need to tell you that this is incredibly unrealistic. When my father went to Stanford University for a doctorate in education he was placed with a team of 20 other grad students for the purpose of conducting “educational research” with the goal of publishing their findings. My father was the only one who had ever taught public school. In fact in his 47 years in public education, holding every position imaginable from teacher to superintendent, he has yet to encounter one of these so called education researchers who has spent any substantial time in a classroom as a public school educator. These are the people who are “leading” the charge towards “better” more “effective” public education. God help us when the West Point officer leads us straight into an ambush because she or he only knows theory and data, not what it is like to actually be in a combat situation.


        Carlos Moreno Los Osos High School English Department Chair

        September 16, 2015
  2. Michelle said:

    Until you’ve been the great teacher trying to continue being great in the face of huge class sizes, you really can’t state these claims. Thank you for your coments, Bill. You made some GREAT points!

    August 29, 2015
    • Hi Michelle. There are a number of great teachers who do a fabulous job with large class sizes. I do think reducing class sizes would make a difference to them. We need to support our best teachers to keep them in the professional and to ensure that they do not burn out.

      What is most frustrating is where less effective teachers claim that they need smaller class sizes in order to be effective. That does not sit comfortably with me. I think this, perhaps, contributes, to why reducing class size does not have anywhere near the impact on improving compared to many of interventions that Hattie points out in his research.

      Even more frustrating, I have worked both with large classes and small in my career, is when class sizes are small, some teachers do not make the most of it and they are complacent – so disappointing.

      Though, I do think I would rather are for less contact time for teachers as opposed to smaller class sizes because of the learning that could take place for us to become better practicioners if we had that bit more time. But then again, if we gave every teacher an extra two hours in a week, who would use it wisely and who wouldn’t?

      I guess what I am really trying to say is that I want to do more for our great teachers.

      August 29, 2015
    • Apologies for not saying this in my first reply Michelle. Thank you for contributing to the conversation.

      August 30, 2015
  3. H. Machtay said:

    I teach a portfolio-based project-based curriculum with students using computers. I’ve often had one section with 38 students and another section of the same class with 29. The larger class falls behind in curriculum. In the smaller class I’m able to give more attention to individual students, and get to know their strengths and their needs.

    That’s just my classes. What about the Chemistry lab class with 38 students? How many of those young people never really learn to do the tasks, never get hands-on time, never get one-on-one attention from the teacher. (If I’m getting heated here it’s because the private school down the block has 10 students in a chemistry class.)

    I know I’m one of the “good ones.” I’ve never received below outstanding rating from any admin. I treasure the time I spend with students in the classroom and do not want less contact time. When I was struggling as a first year teacher I found my mantra: “These are children and they want someone to care about them.” All I’m saying is: It’s easier to care about 27 at a time instead of 38.

    August 30, 2015
    • Thanks for contributing to the discussion. You raise some important considerations.

      I think that reducing class size helps but it is not the panacea that some would claim. I agree, staying on track with curriculum is a challenge and reducing class size would allow students to get more hands on skills development in a chemistry lab.

      Hattie’s work suggests that reducing class size is not as effective in improving student learning outcomes compared to a lot of other teaching strategies and interventions. This is the key. Teaching is complex and just by reducing class size there is no guarantee of instant improvement in learning. The quality of teaching and teachers is what make the biggest difference.

      Saying that, in disadvantaged area, reducing class size is perhaps shown to have a bigger impact on learning when young children have greater contact time with teachers that care about them.

      I have worked in public schools with classes in the low thirties and in private schools with classes in the low 20’s and teens. It is amazing that the instructional quality between private and public schools does not differ that much in my opinion. You are, therefore, entitled to be frustrated and angry. Even more so, when you see that some teachers in private schools do not take advantage of the good conditions that they enjoy to improve their teaching and student learning.

      All the best to you.

      August 30, 2015
  4. Jennifer said:

    I’m a middle school teacher and I disagree with this entire premise.

    First, the fact that you believe most teachers are inherently ‘lazy’ because they don’t necessarily appear to do more for students when class sizes are smaller is disrespectful of teachers in general. It perpetuates the view held by the general public that teachers are lazy and greedy. Teaching is one of the most disrespected and unappreciated professions in the US, despite the fact that it is a challenging job and those who teach go into it because they want to make a difference.

    Teachers are already incredibly overworked as a rule. Perhaps a school that reduces class sizes adds to a teacher’s workload in other ways–committees, clubs, coaching, mentoring, you name it. These additional duties are rarely mentioned in discussion about teacher workload.

    If you don’t see a teacher immediately change his teaching practice because this year he has smaller classes, perhaps it’s because he finally feels like the workload is more manageable. Maybe he was on the edge of burning out. Or perhaps it’s unreasonable to expect teachers to turn on a dime when a policy changes. Maybe he is reluctant to adjust his instructional methods because he doesn’t trust that the district/school are committed to keeping small classes. The amount of mandates and policy changes that teachers deal with in a given school year is absurd, even more so given the fact that before a new policy has been fully implemented, it’s replaced and sometimes added on to with something else. It’s difficult for teachers to know where to invest their energy with this level of bureaucratic indecision.

    Secondly, I hear you say research shows that reducing class size isn’t as important to student achievement as other strategies. I wonder if you differentiate between achievement and learning as I notice you use them interchangeably. From my perspective as an educator in the classroom ‘trenches’, these are two separate concepts.

    Achievement is based on quantifiable outcomes through testing.

    Learning is an internal process of building understanding through engaging in meaningful activities.

    As a former ‘high-achieving’ student, I have direct experience with this–straight A’s and high test scores did not mean I actually learned content. Those things represented how well I played the game of school. In fact, I can tell you very little about the classes I aced in high school and as an undergrad in college. It wasn’t until I was in graduate school, when I connected deeply with the content and the professors, that I finally saw the difference between ‘achievement’ and learning. My relationship with my professors and their modeling of expectations that full engagement in understanding was of primary importance facilitated myself to become an authentic learner.

    Being an authentic learner can and does lead to achievement, but achievement does not necessarily demonstrate authentic learning.

    I am foremost concerned with student learning because that is ultimately what will serve students best in their lives. Achievement will happen when the focus is on learning, but it may not be identifiable on a standardized test or at a specific age.

    And I am absolutely certain that class size matters when it comes to student learning. Case in point: I regularly ask my students for feedback. At the end of this most recent school year, when I had 35 students in a class versus the previous year, when I had 25, a common thread in feedback from the kids was that they didn’t have enough access to me and that affected their learning. Imagine my disappointment. My job doesn’t necessarily get easier with smaller class sizes, but I am able to impact student learning much more significantly, which is why I became a teacher.

    August 30, 2015
    • Thank you for contributing to the conversation Jennifer.

      The post was intended to spark thought and consideration as to the impact of class size.

      I would like to clarify a few things though. Firstly, at no point do I claim that teachers are lazy and perhaps this is your interpretation of the post. Please refer to the last paragraph where I do state that ‘most teachers do work very hard.”

      Secondly, the post does not dismiss reducing class size as not important but, perhaps, comparing it to other strategies for improving student learning and achievement it is not as effective.

      You make a good point about learning and achievement. Hattie’s research clearly states achievement. I have, as you say, used the terms learning and achievement interchangeably, which may not be a good thing to do.

      August 30, 2015
      • Jennifer said:

        Hi Richard,

        I apologize for putting words in your mouth. You did not SAY teachers were lazy. Let me clarify how I drew my conclusions quoting your words:

        “student numbers in classes are perceived to be directly proportional to teacher workload” and “If all schools were to reduce class sizes tomorrow, while pleasing some teachers in terms of their perceived workload” (From my perspective, there is an undertone of criticism in these words especially in using the word ‘perceived’, implying that teachers’ main agenda is to reduce their workload, not to support student learning.)

        “This is not what teachers wanted to hear at all.” (Again, an implication that teachers want class sizes reduced to make their lives easier and are not concerned with how class sizes affect student learning.)

        “If professional practice is poor…” (This is the first reason you list for why class size reduction doesn’t necessarily work. Why is it your assumption that more teachers than not are ineffective?)

        “When class sizes are lower, some teachers do not modify instruction accordingly. Many of the methods used with large class sizes are not always effective with smaller groups.” (You make a blanket statement without any examples or evidence. Why do you think teachers don’t modify their instruction? Again, there is an implication that teachers don’t WANT to do the work to accommodate smaller class sizes.)

        “This, however, relies on the assumption that with small class sizes, the teacher will give more time to feedback. Even then, how do we know if the feedback is actually going to be effective?” (You question teacher work ethic (again) and effectiveness here. Why would you hire a teacher that you didn’t feel was qualified to guide students in their learning?)

        “This post does not mean that class size is not important but without effective teaching it does not make much difference other than to personal workload in terms of marking and, possibly, teacher classroom management.” (Nothing matters more than teacher effectiveness, but effective teaching doesn’t happen in a vacuum. The context of teaching impacts teacher effectiveness INCLUDING workload, behavioral interventions, parental support, administrative support, supplies, AND class size, along with a myriad of other things.)

        Tacking on a sentence at the end of your post acknowledging that teachers work hard does not negate the repeated implications in your post that most teachers are not effective and are more interested in reducing their work than in student learning (thus where I came to the conclusion that you believe teachers are generally lazy).

        Teachers should be treated as professionals–their daily experience in the classroom should not be discounted. We know our classes and individual students better than anyone, and we know that class size is SIGNIFICANT in terms of a student’s learning experience in the classroom.

        August 30, 2015
      • Thank you for taking the time to read the post. I appreciate the feedback that you have given me personally in saying how the post made you feel.

        All the best with your teaching endeavours.

        August 31, 2015
      • Carlos Moreno said:

        Can I just say that Hattie is a University Professor from New Zealand who is in the business of telling American Public School Educators how to educate. And our politicians and administrators are actually listening… This would be truly bazaar if it wasn’t so scary.

        September 17, 2015
      • Thank you for contributing to the conversation Carlos.

        I understand that you are frustrated with class size in your current school. I would agree that there are schools where class sizes are too large. When looking at the impact of reducing class size, context is everything, but I do not feel we should be so quick to throw out educational research on this topic or any other for that matter.

        I believe that Hattie’s research has been incorrectly interpreted by policymakers in many countries and this interpretation has not helped teachers in many respects.

        Hattie does not claim that reducing class size will not have any impact on student learning. His research notes that it does have a positive impact but does not make a significant difference compared to other instructional methods employed by teachers.

        In some cases reducing class size may have a huge impact, depending on the school context; the teacher, the class, the students and the level of socio-economic advantage disadvantage in the area.

        I mention in the post that reducing class size may not necessarily improve learning. There are cases where teachers are very fortunate to work in schools with low class sizes and there is not any significant change in methodology in taking advantage of the situation to improve student learning.

        I hear from teachers like yourself, who appear to be doing a great job with large classes, too large in fact, that we are not able to serve the students better by making the classes smaller. I am hugely concerned, however, when there are teachers who have much smaller classes but the teaching practice is poor, or there is no improvement. These cases do exist.

        I question if we reduced every teachers class size by 5 students tomorrow, would student learning be better in every class? For some classes, yes, but for most classes, I think not.

        September 17, 2015
  5. Scott Milne said:

    An interesting discussion. At the top of Hattie’s list of things that have an impact is Feedback. Surely, feedback can be more effective and more targeted with small classes? In fact, it would be possible to argue that many of the factors are correlated to class size?

    What gets my back up with Hattie is that his research is used to hit teachers over the head with by Right Wing governments, saying that “class size doesn’t matter”, without recognising that actually, many of the things that Hattie says ARE important directly relate to how many students you have in your class.

    January 31, 2017

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