How Important Is Class Size?

Class size is one of many factors to consider when choosing or evaluating a school.

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 less 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 for the early grades.
  • Gains are stronger for students who come from groups that are traditionally disadvantaged in education-minorities and immigrants.
  • 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 benefit of lowering class size. A recent study published in the American Journal of Public Health revealed that reducing class sizes in elementary schools may be more cost-effective than most public health and medical interventions. This is because students in smaller classes are more likely to graduate from high school, and high school graduates earn more and also enjoy significantly better health than high school dropouts.