Research Is In: The Real Impact of Class Size and School Diversity

Picking the right kindergarten for your child can be an overwhelming process. To help you make an informed decision about your child’s schooling, here’s the research behind three common questions many parents ask.

What Are the Benefits of Diverse Schools?

Nearly half of Fortune 100 companies—from Apple to Xerox—argue that in order for businesses to succeed in today’s global economy, their workforces must include highly trained employees of all races, religions, cultures, and economic backgrounds. They also say it’s critical that college graduates enter the workforce with experience in sharing ideas and viewpoints with diverse groups of people.

Schools can be integral in establishing this experience with diversity early on. A 2016 report by the Century Foundation found that students attending diverse K-12 schools have critical opportunities to learn about each other’s backgrounds, increasing the exchange of new ideas and challenges. According to the report, this melting-pot dynamic improves cognitive skills—such as critical thinking and problem solving—and applies to all students, regardless of race or socioeconomic background.

Research shows that racially diverse schools give students more opportunities to learn about each other, which leads to improved critical thinking and problem solving skills. Wells, Fox, & Cordova-Cobo, 2016

Compared with racially homogenous schools, diverse schools also have smaller achievement gaps between students of different racial backgrounds. For example, a study (referenced in the Century Foundation report) of racially diverse, multidistrict magnet schools in Hartford, Connecticut, found the achievement gap between students of different races was reduced on state reading tests by third grade.

The takeaway: School diversity is important, setting children up for success during and beyond school. Companies want graduates who are not only academically proficient but also able to work well in diverse teams.

Should I Hold My Child Back Before Kindergarten?

Many parents wonder if they should delay their child’s entry into kindergarten by a year, a strategy known as redshirting. Children who have been redshirted are older than their classmates, which may lead to some academic advantages. A 2013 analysis published in Educational Evaluation and Policy Analysis found that children generally begin kindergarten between the ages of 4 and a half and 5, but roughly one in 20 children starts between the ages of 5 and a half and 6 years old.

Research findings are mixed on this issue, with inconsistent results.

A 2006 study also published in Educational Evaluation and Policy Analysis found that in an average kindergarten class, older students tend to perform better academically, display more self-confidence, and demonstrate more motivation to learn when compared with younger students. Older students are also less likely to be held back a grade. Additionally, in 2015, the National Bureau of Economic Research found that delaying the start of school by one year can yield mental health benefits such as a reduction in inattention and hyperactivity in children.

These effects appear to be temporary, however. The advantages of redshirting generally disappear by third grade, according to a 2015 study published in AERA Open.

While redshirting can have short-term academic benefits, students that are held back are more likely to have academic and behavioral issues as they get older. Huang, 2015

That study also found several disadvantages to being redshirted: Older children are more likely to be placed in special education programs and have a higher prevalence of behavioral and substance abuse problems as they advance to higher grade levels. They are also more likely to drop out of high school, since compulsory attendance laws keep them in school for a shorter number of years compared with younger students.

The takeaway: There are advantages and disadvantages to redshirting children. Before making a decision, carefully weigh how the decision can impact your child both in the short and long term.

Does Class Size Matter?

When evaluating schools, the first thing parents often look at is the class size, or number of students being taught in a particular classroom. Yet while smaller classes can be beneficial for students, research suggests that it's not guaranteed.

A 2014 analysis by the National Education Policy Center found that smaller classes generally lead to higher test scores for students—especially in earlier grades and for students from disadvantaged backgrounds—but only if teachers are properly trained and adjust their instruction accordingly.

For example, in smaller classes teachers can tailor instruction to meet students’ specific needs, or spend less time on classroom management and more time on activities that engage students and improve learning opportunities. If teachers make these kinds of adjustments, smaller classes can yield positive results.

Despite these benefits, smaller class sizes may not be cost-effective compared with other improvements. Studies show that highly trained, well-supported teachers in large classes can be just as effective as less-experienced teachers in smaller classes. In a 2015 report titled What Doesn’t Work in Education: The Politics of Distraction, Professor John Hattie concludes that decreasing class size yields only a small net improvement in learning because teachers rarely alter their teaching style when moving from a larger to smaller class.

The takeaway: While smaller classes may be beneficial for students, don’t assume that they guarantee positive results. You should look for high-quality, experienced teachers first and foremost—even if they are teaching in large classes.