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Lesson 4.2

Class Size:
How Big Should Classes Be?

Sure, California class sizes are big. But are they out of line?

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Image: Insect Convention CC WoodleyWonderworks

The number of students in a class is a time-related idea, a proxy for how much time and attention a teacher can give each student. In a small class there is more teacher-time available because it's allocated among fewer students. One strategy for improving educational quality is to cut class sizes.

Let's start with the basics. Class sizes in California are abnormally big.


Large class sizes (measured by comparing the number of students to the number of teachers on staff) are nothing new for California. The graph below shows the average "student-teacher ratio" in each state since 1970. This statistic is a proxy for "class size," but it is really just a best-case statistic. Most actual class sizes are larger than this statewide benchmark. Still, it is safe to expect that the higher the number of students per teacher in a state in any given year, the larger class sizes must be, and vice versa.

California's student-teacher ratio has been among the highest in America for decades. California's student-teacher ratio has been among the highest in America for decades.
More charts like this can be found on at

Clearly, smaller classes cost more than big ones. Does it make a difference?

Yes, Smaller is Better

Like anything in social sciences, context matters. The Center for Public Education (CPE), an initiative of the National School Boards Association, analyzed 19 studies on the subject. They concluded "most of the research shows that when class size reduction programs are well-designed and implemented in the primary grades (K-3), student achievement rises as class size drops." One general conclusion was that the greatest benefits accrue for disadvantaged students in grades K-3, and when there are 18 or fewer students per teacher. A research review by the National Education Policy Center (2014) reaches the same conclusion, and analyzes the different research approaches that have been brought to the question.

...the greatest benefits accrue for disadvantaged students in grades K-3, and when there are 18 or fewer students per teacher.

Class Size Matters is an advocacy organization that provides additional information and research on class sizes, including cost-benefit analyses. International comparisons provide additional perspective on this question.

In 1996, California increased school spending to implement a dramatic class size reduction policy for grades K-3, capping class size at twenty students. This policy change, which was implemented without a phase-in period, created a sudden shortage in K-3 teachers, and schools struggled to find qualified teachers. In the rush to fill positions, schools serving low-income communities were most likely to have to settle for less qualified and less experienced candidates. This dislocation had a lasting and unequal impact. This is a cautionary tale for education reformers:  beware of unintended consequences.

The California Department of Finance estimates that the state spent over $22 billion on incentives for K-3 class size reduction from the program’s inception until it was changed in 2009-10. In the lean budget years up until 2013, the incentives were reduced and the rules effectively eliminated. Elementary class sizes rose steadily as a result, keeping California in last position in the country as far as class sizes.

As part of the new Local Control Funding Formula beginning in 2014, the state is offering districts about 10% more per K-3 pupil if they either commit to reducing class sizes down to 24 or get their teachers’ union to agree to a higher class size. Keen-eyed readers will note that the research referenced above showed a benefit to much, much smaller classes.

Should Classes Vary in Size?

In virtually any school, the number of students in each class tends to be pretty uniform. Walk into two 4th grade classrooms at random, and the number of students will probably vary little. Is this uniformity a mistake? Should classes vary in size?

In an influential speech in 2011 Bill Gates encouraged education leaders to re-examine the rationale for maintaining consistent class sizes, arguing that some teachers are better than others at getting results in large classes. “Conservative estimates suggest that we can save more than $10,000 per classroom by increasing class size by just four pupils. If we pay some of that money to our best teachers for taking in more students, we accomplish three goals at once – we save money, we get more students in classrooms with highly effective teachers, and we give our best teachers a real raise, not just for being good, but for taking on more work.”

Given the very high student-teacher ratios in California, Gates’ comments could be taken as an argument for reducing class sizes selectively, rather than continuing the uniform K-3 class size approach the state took in 1996. Under the provisions of California’s new funding system, which provides extra money for high-need students, local school districts might consider reducing class sizes in schools that serve the highest proportions of low-income students or English learners.

School time varies a great deal among the states and around the world. The next lesson takes up the question of how much time students spend learning.


Which ONE of the following statements is FALSE?

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Questions & Comments

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user avatar
Carol Kocivar June 22, 2016 at 11:32 am
A bit more research on class size...
A June 2016 policy brief from the National Education Policy Center takes another look at the research and finds....
"Despite claims to the contrary by some policymakers, Mathis concludes that reduction in class sizes may prove the most cost-effective school improvement policy overall. In Mathis’ view, money saved today by increasing class sizes will likely result in additional substantial social and educational costs in the future."
Dr. Mathis is Managing Director of the National Education Policy Center.
user avatar
Albert Stroberg May 1, 2016 at 7:12 pm
I looked at my 4th grade class photo (California)- 28 kids and one teacher. How are kids now so needy?
user avatar
asoltero March 2, 2016 at 2:13 pm
Class sizes especially in the primary grades should be kept to no more than (20). Larger classes are not conducive to a highly optimal learning in academic subject areas. Smaller class sizes afford the teacher the time and energy to work more effectively within the class in smaller group settings. Studies have shown that smaller class sizes score higher on tests, receive better grades and exhibit better attendance. Reducing class sizes in the early grades improves the achievement gap by up to 38%. Students display less disruptive behavior in classes and teachers spend less time on discipline having more time for instruction. Teachers in smaller classes can diagnose and track student learning and differentiate instruction in order to meet students needs. In smaller classes students spend less time off task or not focusing on the task at hand and have greater access to technology.
user avatar
iemailjillian February 29, 2016 at 5:39 pm
Smaller class sizes are effective because more time can be spent on each person when they need more time.
user avatar
Angelica Manriquez February 29, 2016 at 3:53 pm
25 students for a 1 teacher and a 1 helper woud be ok. Not all for 1 teacher
user avatar
Will Kimbley February 5, 2016 at 12:24 pm
While I completely agree that smaller class size has the potential to increase student achievement, the research shows in practice it actually has a very small effect size. John Hattie's research doing a meta-data analysis of over 800 studies covering some 80 million students shows that reduced class size has only a 0.21 effect size on student achievement which is 107 out of his list of 138 studied interventions in education.
The reason is the research shows that by and large teachers do not teach any differently with a smaller class size than with a larger class. If a teacher does not take advantage of the smaller class size to change the way they teach, it is not going to have much effect.
user avatar
KimS September 15, 2015 at 10:27 am
The issue I'm seeing with the smaller class size incentives is that districts are creating an increasing number of combination or multi-generational classes, with a mix of grade levels in one class. But nobody seems to be tracking these figures.
When a school designs this as an integral part of its pedagogy, that works. But when it is forced on schools for logistical reasons of budget, the kids and teachers suffer. My kids go to an IB school that's designed as an age-appropriate, sequentially-building program. Combo classes are causing parental worry and a lot of time and effort for the teachers in both classroom management and curriculum re-designs.
I don't think this is what the LCFF lower class size mandate intended to do, and nobody seems to be tracking whether the class sizes are combos or not. It's a huge loophole in the law.
user avatar
davidstephen72 July 12, 2015 at 3:54 pm
Smaller class size makes no difference unless the teacher teaches differently than in a large class.
Our local district has an "Early Reader/Late Reader Progr set in stone. This is supposed to reduce class size.
However, it is s pernicious negative practice???.
Early Readers are labeled as slow readers and tracked thereafter in the Early Group. Think of how this affects each "Low/Slow Reader's" self image and motivation.
This dramatically affects the parents'/guardian's sge of the child.
Slow-Low-labeled Readers never exit this status and, unfortunately have little or no contact with Good Readers.
user avatar
Tara Massengill April 28, 2015 at 2:13 pm
When I was in 5th grade (I graduated high school in 1999), there were 32 kids in my class. My teacher had no problems teaching us, or keeping us on task. My daughter is in 5th grade this year, and her class has the same number of students. According to my daughter, her teacher is constantly having problems keeping the class on task. I've spoken with other parents whose children are in the class, and they say their children have said the same thing. Is it a sign of the times, a sign of the State of California's education system being that much different from the education system in the State of Tennessee, of is it a sign of the teacher being ill-prepared in general?
user avatar
aimeef23 April 27, 2015 at 4:08 pm
Class size is definitely a hot topic. Some people and research states small classrooms are better and kids thrive as opposed to a larger class size. I think there is a point in which both a small and large class are harmful. There should be enough kids in a classroom to have meaningful discussions on topics. You need opinions and kids need to feel like they can have open discussions. When there are too many students many kids are lost and their voices are not heard.
user avatar
cnuptac March 22, 2015 at 2:55 pm
My husband teaches high school and in one math class he has 55 kids there are no limits for high school and no parent helpers. It's wrong he can't get to every child to help them stay on track during his paid hours so he goes to school a hour and a half early for helping kids if they want it for free and some do come but the kids that are the most behind don't even try and get the extra help Heidi
user avatar
lb2vta March 19, 2015 at 11:37 pm
My daughter has a fabulous second grade teacher, but the larger class size (27) does make her job more difficult. I assist in the classroom 2x per month and notice a difference (for the better) when someone is absent.
user avatar
Brandi Galasso February 22, 2015 at 7:48 pm
Class size matters especially when those classes are not being given the supplies or tools needed to accommodate teaching a larger size class. It's not fair all the money schools are lacking can be found in the paychecks of district employees. Instead of hiring more district employees, put a teacher aide in every classroom. It's another adult it helps immensely and also is a witness in case any thing unprofessional in classroom happens.
user avatar
davidstephen72 July 12, 2015 at 4:01 pm
How about recruiting parents, guardians, grandparents other caring adults, teachers in training retired teachers, etc. to come volunteer in the classroom.

This practice explained the great success of our Mommy and Me Programs.

However, Givernor Brown and Senator Carol Liu of Burbank KILLED THE PROGRAM. SHAME ON BOTH!
user avatar
David B. Cohen April 7, 2011 at 11:00 pm
First, I have to admit I haven't read class size studies. From what I've heard, those finding class size doesn't matter much have not been based on major differences. From an anecdotal perspective, I'll go along with the idea that 10% doesn't matter in my high school English classes. If my class of 30 goes to 27 or 30, it's a blip. Unfortunately, people are using the study conclusions and ignoring the numbers, arguing that class size doesn't matter, period, although the changes I'm hearing about in some California classes are more on the order of 30, 40, 50% in some cases, if we compare across a couple of years. Those incremental gains don't look as bad. We'll just go from 21 to 24. Okay, but the budget is bad - you can go from 24 to 28, can't you? Well, now we just grew class size by 33%. Any studies to say that won't matter? I'll tell you anecdotally that it certainly matters. For high school teachers, you also have to keep in mind the total student load. The NCTE guidelines on this topic suggest that in order to provide quality instruction in the full spectrum of English Language Arts, a teacher's student load should be 80. In California, full time secondary-level English teachers routinely have 150-180 students.

I find it curious that you offer words of caution about unintended consequences for those who want to reduce class sizes, but express no caveats about the opposite argument. I find it troubling that you pass along Bill Gates opinions on education so uncritically despite his lack of credentials in the field and his increasingly obvious agenda in edreform, which many of us in the classroom find increasingly alienating and even hostile.
user avatar
Steven N June 23, 2014 at 5:40 pm
K- 3 issues only: Certainly Mr. Gates is not a research expert in this field. Micro-economists using rather substantial large data sets show the K-3, economically disadvantaged student impact is both statistically significant (learning months per year) and highly dependent on implementation! California's - everybody-all-at-once was a disaster because it widely distorted the market for good K-3 teachers. Now this method becomes a real option for 'high concentration' LCFF districts that want to use a good portion of the 20%-50% of per pupil Supplementary $ to use this method. Outcomes? Depends on implementation and highly effective teachers!
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