How important is class size?


By GreatSchools Staff


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"?


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:

Next page: Why reducing class size matters in the early grades

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, 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."


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 recent years there has been a movement across the country to reduce class size 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. Currently, well over half the states have class-size reduction programs for their public schools.

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.

Reducing class size is an appealing and visible way for states and public schools to show that they are improving the quality of education. Because smaller classes allow teachers to devote more time to instruction and less to classroom management, smaller classes are popular with teachers unions and administrators. 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

In addition to high costs, reducing class size can have unintended consequences. When California reduced class size in 1996, the state found that it did not have enough veteran teachers or classrooms to meet the challenge. Schools were forced to hire new teachers and add portable classrooms to accommodate the state mandate. Schools faced a dilemma: Was it really better to have smaller classes with an inexperienced teacher or larger classes with experienced teachers?

Voters in the state of Florida approved a class-size reduction amendment in 2002 that requires classes to have no more than 18 students in pre-kindergarten through third grade classes, no more than 22 in fourth to eighth grade classes and no more than 25 in high school classes by 2010. The state Board of Education estimates that Florida will need to spend $2 billion to build enough classrooms to meet the demands of the amendment.

Next page: Why smaller classes aren't enough

Why smaller classes aren't enough



How important is school size?



Other important factors to consider

Teacher workload


Team teaching




Next: Making the most of larger class sizes