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Class Size DOES Matter


“…class-size reduction programs in California and elsewhere – especially Florida – look foolish.”

So says Justin Snider from the Hechinger Report in a guest post at the Washington Post’s Answer Sheet.

I find these kinds of pieces very irritating for a number of reasons (and I am also trying hard to not let my unhappiness with Hechinger’s financing of the research for the LA Times research on “value-added” teacher assessments get in the way of looking at his piece relatively objectively. The Times used it for their insulting series making teacher “scores” public).

First, I wish all “school reformers” who live in academia would read Corey Bower’s post “First Day Of School: Where Are You?” Corey is a former K-12 teacher who now is at a university and writes:

And yet, I now find myself up in the ivory tower consorting with others who regularly cast stones at the lowly teachers…. And you know what? Most of them couldn’t hack it in the classroom either.

Mr. Snider teaches writing at Columbia University, and says he was a former high school English teacher. I did a little research and, though I couldn’t find out how long he taught in a high school or where he taught, I did find that he was a course examiner for the International Baccalaureate program. I assume that means he taught IB classes.

Well, I have a large IB class, and it works quite well. Of course, these are just about the most motivated and disciplined students you’re going to find anywhere.

I’m very confident in my ability as a teacher. But if you gave me the same number of students for my mainstream ninth-grade English class in an urban school, I’d go nuts (and I don’t think it would be a great experience for the students, either). I can’t imagine what it would be like with first-graders.

Finally, I know some say the research questioning class size’s role on academic achievement is very convincing, but when I googled “research on class size” I found most of the research to be pretty positive. It would also be important to note education researcher Corey Bower’s observation on class size research:

I think one of the problems with class size research is that there isn’t a whole lot of variation in class size across most schools, or after implementing most policies. Let’s say a district decreased class size from 26 to 24 — would we expect a huge, and easily measurable difference? Probably not. And yet researchers are trying to quantify these differences and finding out that there’s not much there. If, on the other hand, we reduce class sizes from 25 to 15, we would expect differences to appear. The Tennessee STAR study remains the most rigorous evaluation of large differences in class size and found large, positive effects of changes of this magnitude.

So, what do you think? Does class size matter? Or do you agree with Mr. Snider that it’s “a luxury…we can no longer afford”?

(The tragic loss of reduced class size is the title of an Op-Ed piece in the San Francisco Chronicle by Delaine Eastin, former California superintendent of public instruction)

Author: Larry Ferlazzo

I'm a high school teacher in Sacramento, CA.


  1. I honestly can’t see that larger class sizes will improve — or not hurt, I guess is the angle here — student learning.

    I’ve always found that struggling students rarely respond if you cannot treat them as individuals. Larger class sizes make it hard to do that. Students respond when teachers have a speedy turnaround on assessment. Larger class sizes make it harder to do that.

    For example, I teach HS English and try to return assignments within one class. Marking essays for a class of 20 is tough, 25 is very tough, but 30 is excruciating. These numbers seem like small differences, but they add up to hours and hours of extra marking. And with 30 students per class… conferencing is all but impossible.

  2. As a first year teacher 20 years ago, I was overwhelmed by my class of 38 third graders. I did my best, but I know I did not serve them well. My ELLs needed so much; it was incredibly difficult to get to all of them in that setting. The same happened several years in a row. One year, I had 40 students!

    My school district has gone through a myriad of changes over the years resulting in more staff and smaller classes. During the past five years, I’ve never had more than 16 students. The social and academic benefits to my students have been immeasurable. I can honestly say I have been able to meet each and every student’s needs. Small class size allows students to receive the maximum attention they deserve.

  3. Hello again Mr. Ferlazzo. I commented on your blog about Arne Duncan. I am in Dr. Strange’s EDM 310 class at the University of South Alabama.
    I believe class size is important but it doesn’t matter. I don’t believe it is a pass or fail difference, it take a little more discipline and responsibility to show up 🙂 but that is an important skill to learn.
    As a student I tend to do better in smaller classes and I enjoy them. The teacher knows my name and we have more class discussions. My my larger classes my mind tends to wander off. In my public speaking class we have about 115 students but we also have smaller group taught my GS’s. My group is about 15 students and it is a great setting. This may not be true for every student. I realize everyone learns differently and I tend to be a social person, so any class where I can discuss and activity participate helps me learn better.
    Once again, I really enjoyed your post and I look forward to many more! you can contact me at

  4. Class size does not matter if the powers that be want us to teach using the “sage -on-the-stage” teaching style where we just stand up in front of the class and blah blah blah. Class size does matter if the- powers- that -be want us to teach students by providing differentiation in instruction and evaluation in order to meet the various needs of our students. At least, that’s the way I see it.

  5. And, if class size doesn’t matter then couldn’t they greatly reduce the cost of private schools by having 50 students in a class? A popular local private school here is $17,000 a year and if they had 50 students per class it could drop to $9,000 say (about half) – still over $2,000 per student more than our local public schools get, but half price! Who wouldn’t go for that if class size doesn’t matter?

  6. I began my teaching career in an urban classroom with more than 30 students. Having nothing to compare the numbers with, I did whatever I could and found that “divide and conquer” was most effective so I generally set up my classrooms with four groups of eight students heterogeneously grouped.
    In my 9th year of teaching, Los Angeles got class size reduction. My class of 30 1st grade ELLs became a class of 20. My four groups of eight became three groups of seven and the difference was AMAZING! I was able to provide my lower students with the additional support they needed and provide enrichments for my more advanced students.
    I have been teaching kindergarten for the past 13 years. Last year, the class size was raised to 24 because of budget cuts. When I read the Post article about class size I was furious! Just the difference four extra students greatly impacts instruction. Even minor things like seating become trickier and makes flexibility in grouping more difficult. Not to mention that the smaller class size facilitated varying degrees of mainstreaming for primary special ed students, many of whom have difficulty in a more crowded classroom.
    Class size reduction is worth every penny spent! If people want to cut education budgets let them investigate the bloated bureaucracies that exist.

  7. I can affirm and confirm that class size is one of the most important factors involved in teaching and learning success.
    I agree with Ryan about struggling students or the ones who are less skilled for whatever reason.

    I have learnt from my EFL teaching experience that smaller groups (15-20 maximum) work and behave better.

  8. You seem to have picked a very adequate topic which affects students across the country. Asa college student at the University of South Alabama in Mobile, my classes range in size depending on how hard they are. Yet I have seen first hand the difference in small classes and larger classes in regards to my daughter. Baldwin County in south Alabama has experienced considerable cuts in their educational programs thus causing some schools such as Orange Beach Elementary to go from 3 second grade classes to 2. This occurred 2 years ago with my daughter. The school did not get rid of the students, just the teacher, then split the extra among the remaining two classes. This doesn’t help the students at all in my opinion. Thanks again for your up to date blogs, which I have enjoyed reading. You can read further comments on my EDM blog for class about your blog and others at, Shellie Miller’s Blog

  9. I wrote on this subject for a now defunct chain of suburban DC papers back in 2002. here’s the link for that piece

  10. There is data to support both arguments. Consider this, a larger sized classes require more work on teachers who already give much of their own time. Many teachers sacrifice family time to grade papers, comment on student writing, and to call parents. Those same teachers will probably continue to do so until the completely burn out. There are also those teachers who, within their rights, work only the hours for which they are paid. A larger class for them means less will be done, or done in a timely manner at the very least.
    “Imagine two households, one with four children and one with two,” says psychology professor Joseph Rodgers of the University of Oklahoma.. “In one household the parents spend a lot of quality time with their kids, the house is filled with books, and the food on the table is nutritious. In the other the parents pretty much ignore the kids and sit around watching TV. What do you think is more important: The number of children or the quality of the parenting?”
    It is the time that matters for both teachers and parents. Many of us sacrifice that time with our own families for yours.
    The bigger the class the more will be required o the teacher in terms of time.

  11. an additional comment – my three AP classes currently have 36, 38 and 39. The real problem is that in a 45 minute period it is hard to get everyone involved in the discussion, which should be part of the experience.

  12. First, thanks for the link.

    Second, I think one of the problems with class size research is that there isn’t a whole lot of variation in class size across most schools, or after implementing most policies. Let’s say a district decreased class size from 26 to 24 — would we expect a huge, and easily measurable difference? Probably not. And yet researchers are trying to quantify these differences and finding out that there’s not much there. If, on the other hand, we reduce class sizes from 25 to 15, we would expect differences to appear. The Tennessee STAR study remains the most rigorous evaluation of large differences in class size and found large, positive effects of changes of this magnitude.

  13. Class size absolutely matters, especially when talking about struggling students and schools. When students come to school several years behind in every subject, frequent small group instruction and one-on-one attention is their only chance to catch up. Also, in many places, the amount of forms and other reporting requirements goes up for each student who is below grade level. That easily translates into several more hours of weekly work for the teacher, which subtracts from that teacher’s ability to provide high-quality instruction. When we refuse to put a reasonable number of students in a class like that, we set the teacher and the students up for failure.

  14. Also, @ Brian–I’ve been DYING to ask one of the class size doesn’t matter types that very question for YEARS! They sit and tell us regular folks that we should be OK with 30 plus kids in each class, while their kids sit twelve to a Harkness table in a tony private school classroom. It smacks of classism and hypocrisy.

  15. Amen to Elona Hartjes! If you expect quality teaching, differentiated instruction, cultural relevance and responsiveness, and student centered hands on learning experiences, class size absolutely matters. Drill and kill can be done with any number of students that can fit in a room.
    For Trudy Norton: If you equate grading papers with a family having “quality time”, you are missing the point. Grading papers is like doing laundry; it needs to be done, but clean clothes are not the glue that binds a family. Similarly, graded papers (regardless of the grades earned or given) are not necessarily representative of student learning.

  16. I teach 5th grade in an urban California district. I’ve always had 35+ students in my class. It does make a difference on those days when a few students are absent.

    This year, only 27 students on my roster showed up for the first three days of school. Wow, what a difference! I know that 27 may still seem like a lot to many teachers, but I was in seventh heaven! Needless to say, the district took care of those numbers very quickly, and I am now back up to 36. But it was good while it lasted…

  17. i think of this argument as it relates to other professional working fields. for example, if you consider a financial adviser and the average clientele load for this profession, many best practice arguments state that fewer clients with more quality time spent per client is best. this is also true of social workers, psychologists, occupational therapists, coaches, doctors and countless others.

    if teachers are meant to be providing the best possible practice for their students (per our TeachingCodeOfEthics) and the national movement is to evaluate teachers as if they are offering a measurable service to their “clientele”, then it only makes sense to place teachers in a position in which they can be successful and in conditions under-which they can practice their art.

  18. I think class size does matter, especially in secondary schools. In a classroom reduced from 25 students to 15 students could help the students significantly. Students would benefit from the smaller class size by getting more one on one time with the teacher. Furthermore, teachers could benefit because a smaller class would be easier to manage than a large class. Most importantly, a very well manage classroom would make the learning experience more productive for the students. I think it’s much different for college students, I’ve had classes with as many as 180 students but I did not suffer because the classroom was large. College students are adults and are expected to be responsible, with that in mind I think the college student would be able to handle a large classroom.

  19. Of course class size matters! It is one of only four education reforms that have been proven to work through rigorous evidence. perhaps Mr. Snider isn’t aware of how much it matters, because his writing class at Columbia Univ. is capped at 14 students per class! Intro writing classes at Harvard are capped at 10. And yet these elitists seem quite content to burden high-needs poor and minority kids in classes of 30 or more. This is hypocrisy beyond belief.

  20. I believe California schools have some of the largest class sizes in the nation, over 40 students often while other states consider more than 20 a large class. I think it is significant that when my low-performing middle school got targeted funds to improve achievement, reduction of class size to 25 was a key component. In co-teaching classes, the ratio drops to 1:13. This provides for A LOT more individualized attention, conversation, and collaborative work. When I had 37 students, I wanted individual desks for a more controlled room environment. With 25 I have students grouped together to facilitate more student-directed learning. Research statistics can be tweaked to prove just about any point, but any teacher who uses active, differentiated instruction can tell you how greatly class size matters.

  21. The point I always like to make is that it is a really critical condition of work issue for teachers. All of the teachers who have commented, and your own post, point to the enormous administrative (grading, etc) burden that having a large class places on a teacher. This is why when classes in college hit over 30, the instructor usually has TAs to help grade papers, etc.
    I know it’s not fashionable to talk about what makes working in schools more pleasant for teachers these days, but there is a reason it’s important for students and their families. If your child’s teacher is trying to grade 200 essays (5 periods of secondary classes with 40 students average) or 105 pieces of work in writing, math, and science (an upper elementary class of 35), how much quality analysis of that work will be going on? That combined with standardized testing is guaranteed to make your child nothing more than another “widget” to that teacher.

  22. Thanks, everyone, for your comments.

    Valerie Strauss from The Washington Post has republished this post. If you get a chance, I hope you’ll consider leaving a comment there, too.

    You can find it at:


  23. I went to a small school in Louisville, KY where I had a graduating class of 50 students. All class sizes were 25 or less. Guess where that school is when it comes to ranking on the State test….1st. And it was a public school.

    You won’t find me arguing against smaller class size. It made a huge different in my education.

  24. I taught 4th grade for many years, with class sizes of 32 to 36 (despite a theoretical contractual maximum class size of 34–the bureaucrats always found some sneaky way to evade the contract). As soon as class size reduction for K-3 came in in California, I switched to 3rd grade. The difference a smaller class size made was phenomenal-discipline problems virtually disappeared, small groups with center rotations allowed for real differentiated instruction, and students learned and grew. We formed a community, instead of working in a factory.

    The notion that we cannot “afford” smaller class sizes is ludicrous–the paltry sums spent on our schools (most of which still goes to bureaucrats and administrators who provide no meaningful benefit to students) are dwarfed by the expenditures we make on puerile “entertainment” and junk food, not even to mention war-making and prisons. The huge distortion in our society’s priorities is strikingly illustrated by David McCandless with his visualization of the time spent to create Wikipedia compared to hours of television watching by US adults:

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