How much attention do students at your school get? Class size is one factor to consider when evaluating a school’s effectiveness. But small class size alone does not ensure a good education. The quality of the teaching, the school leadership, the size of the school, the amount of parent involvement and other factors are important to consider, too.

What’s the difference between class size and student-teacher ratio?

GreatSchools publishes class size information for schools in some states and student-teacher-ratio information in others, depending on what’s available in each state from the respective state Department of Education. It’s important to understand the difference between these two types of data and what they indicate about your school.

When you see class size stats on GreatSchools’ school pages, the number refers to the average class size at the school. Some classes may be larger or smaller than the average number you see. This is especially true in schools which have state-mandated class sizes, particularly in the lower grades. Schools that have mandated lower class sizes in grades kindergarten through 3 may have larger class sizes for the upper grades.

Student-teacher ratios are based on the total number of school instructional staff divided by the total enrollment of students. So this number may include specialist teachers in the arts, literacy specialists, physical education and special education teachers, who may teach smaller groups of students. As a result, student-teacher ratios may show smaller numbers than the actual average class size.

Student-teacher ratios, which in many states are based upon full-time equivalent (FTE) teachers, can appear high for schools that have a large number of part-time teachers. If, for example, a small school has four part-time teachers, who each work 25% of the time, the student-teacher ratio at this school would be calculated based upon one teacher instead of four (because four teachers at 25% is equal to one full-time teacher). This will make the student-teacher ratio appear higher than it really is. If you think your school data shows an exceptionally high student-teacher ratio, check with your school principal to find out why.

What defines a “small class”?

Researchers have found that gains in achievement generally occur when class size is reduced to fewer than 20 students.

What are the benefits of small classes?

Numerous studies have been done to assess the impact of class size reduction. Although most studies do show a relationship between small class size and increased student achievement, researchers disagree on how to interpret the results. Because there are so many variables in the average classroom — the quality of the teacher, the home environment of the students, the quality of the curriculum, the leadership of the school — it is difficult to draw definitive conclusions about student achievement based on class size alone.

In other words, strategies effective in one setting may not be equally effective in another. Nevertheless, studies over a period of years have pointed to a number of trends as a result of lowering class size:

  • Gains associated with small classes generally appear when the class size is reduced to less than 20 students.
  • Gains associated with small classes are stronger in the early grades.
  • Gains can be stronger for historically underserved groups, including Black students, as well as Hispanic, immigrant, and low-income learners.
  • Gains from class size reduction in the early grades continue for students in the upper grades. Students are less likely to be retained, more likely to stay in school and more likely to earn better grades.
  • Academic gains are not the only potential benefit of smaller classes. Some research has shown that smaller class sizes can also result in better student behavior, increased focus on classroom work, and stronger teacher-student interaction.

Why does reducing class size in the early grades have a positive effect?

Education researchers suspect that class size reduction in the early grades helps students achieve because there is a greater opportunity for individual interaction between student and teacher in a small class. Teachers generally have better morale in a small class, too, and are less likely to feel overwhelmed by having a variety of students with different backgrounds and achievement levels. As a result, they are more likely to provide a supportive environment. One researcher, the late Harvard statistician Frederick Mosteller notes “Reducing [the size of classes in the early grades] reduces the distractions in the room and gives the teacher more time to devote to each child.”

In the early grades, students are just beginning to learn about the rules of the classroom, and they are figuring out if they can cope with the expectations of education. If they have more opportunity to interact with their teacher, they are more apt to feel like they can cope.

This theory would also explain why lowering class size in the upper grades may not have the same effect on achievement. Students in the upper grades, who may not have had the benefits of a small class in the early years, have already formed their habits, good and bad, for coping with their classroom environment. Simply reducing the class size at this level may not be enough to change their ways.

The movement to reduce class sizes in public schools

In the late 1990s when state coffers were full, it was politically popular to cut class sizes across the board in the lower grades as a way of pointing dollars toward education in a way that would please voters.The federal government jumped on the bandwagon in 1998 with a federal class-size reduction initiative. From 1999-2000, the federal government’s $2.6 billion appropriation enabled states and school districts to hire more teachers and reduce class sizes.

But that program only lasted two years, and since then much of the impetus to reduce class sizes has come on the state level. Most recently, New York State passed a law in 2022 to cap class sizes in New York City schools by 2028. Voters approved a measure to cap class sizes in Florida in 2002. California was an early advocate, passing a law to cap class size in 1996. Many other states have instituted or are considering some form of class-size reduction programs for their public schools.

Capping class size, however, is complicated because of teacher shortages, post-pandemic enrollment declines in some districts and growing enrollment in others, and the cost of new classroom space. Moreover, some states, like Georgia, can grant waivers to schools or districts to sidestep mandated class size limitations. In 2022, the Georgia Association or Educators, warned that such waivers lead to “… larger classes that study after study has shown is not conducive to providing the best teaching and learning environment for our children.”

Because smaller classes allow teachers to devote more time to instruction and less to classroom management, they are popular with teachers unions and administrators, as well as many parents,. Many studies have shown an increase in student achievement, fewer discipline problems, and improvement in teacher morale and retention as a result of class size reduction. But many researchers question whether the costs outweigh the benefits.

Unintended consequences

Reducing class size can have unintended consequences. California is still struggling to find enough veteran teachers or classrooms to meet the challenge. Is it better to have smaller classes with an inexperienced teacher or larger classes with experienced ones? Meanwhile, the  Florida State Board of Education estimated that the state would need to spend $2 billion to build enough classrooms to meet the demands of its class size measure. New York Mayor Eric Adams also cited the cost factor in the state law, arguing that it could cost his cash-strapped city $500 million a year just to reduce class sizes in kindergarten through fifth grade, plus billions more to build more schools and classroom seats. It’s clear that whatever the value of smaller class sizes, it won’t come cheap

Why smaller classes aren’t enough

In California, where class size reduction began in 1996, the research has shown only a modest effect on achievement. This disappointingly small gain has been attributed to the following:

  • Per student funding for class size reduction was not enough to cover the cost for already underfunded districts.
  • School districts had to hire new teachers, many of them not certified, to meet the needs to make their classes smaller.
  • Serious overcrowding issues forced schools to “cannibalize” other needed facilities — special education rooms, child care centers, art and music rooms, gyms — or rent portable classrooms to accommodate the need for more classrooms.
  • The high cost of implementing class size reduction made it difficult to fund other education needs.

The California experience points to an important lesson. Class size reduction, in and of itself, is not the answer to all the problems in education. In order for a classroom to be effective, it must have a qualified teacher and adequate facilities. When weighing the advantages of class size reduction, schools, districts, and states must consider these questions:

  • Will there be enough resources to provide for high-quality teachers?
  • Will there be adequate facilities to provide for the necessary classrooms?
  • Will putting money into class size reduction take away money from other programs, such as art, music, and child care?

How important is school size?

For some students, school size may be as important as class size during elementary school. A 2010 study of North Carolina schools in Educational Evaluation and Policy Analysis found that while school size may not change educational outcomes overall, smaller schools do make a big difference for two specific groups: poor students and those with learning disabilities. In particular, the study found that the largest benefits are seen among students with learning disabilities. Some families, however, still prefer small schools for their intimacy, community, and sense of safety, even if their children aren’t in one of these subgroups.

For high school students, the relationship isn’t as straightforward because students at smaller schools don’t necessarily perform better academically; in fact, one study found that students at medium-sized schools (with between 600 and 900 students) did better academically than students from smaller and larger schools. However, research shows that smaller schools are associated with a host of other benefits for high school students: they are less likely to drop out or be expelled; they have better attendance; they’re more likely to be involved in extracurricular activities; and they’re more likely to pursue higher education.

Other important factors to consider

Teacher workload

In high schools, it is important to consider not only the number of students per class but the nature of the class, and the subject the teacher is teaching. For example, a math teacher might have no problem teaching an advanced math class, or several math classes, with 35-40 students. But an English teacher teaching four classes of 40 students would probably not be able to give the proper attention to written assignments from that many students, and might not give as many assignments because of the large number of students.

Team teaching

Some schools might have classes of 40 taught by a team of two teachers. The class size by itself is not necessarily an indication of the attention students are getting.


Some schools effectively use parents and upper-grade students as volunteers in the classroom. This type of instructional help may not appear in a school’s data about class size.

Is it the right place for your child?

Whether there are 25 kids in the class or only 10, parents need to seriously consider if the smaller school or class will be a good fit for their child.  Will your child hit it off with the teacher?  In a small school with small classes is there an opportunity to change classes if they don’t?  Will a small class mean that a shy child will have to speak up more than they want? Will the child have the same chances for social interactions they would in a bigger class or school? And for older kids, will the school offer all the desired extracurricular activities? There are definite advantages to small class size and to small schools. They’re not right for every student, but they could be right for yours.