One reason why all families benefit from publicly-funded preschool, including families who don’t enroll their children in public preschool, is the increased educational achievement due to peer effects in K-12 schools. As discussed in my new book, From Preschool to Prosperity, these peer effects provide an important “spillover” rationale for why preschool might attract broad voter support.
Empirical evidence finds that everyone in a kindergarten class benefits if a higher percentage of the kindergarten class enters with better skills from high-quality pre-K. The effects on an entire class’s end-of-kindergarten test scores, due to having one additional child who enrolled in high-quality pre-K, are 16% to 50% greater than what would be expected from the direct effects on that individual child’s achievement. Other studies find similar peer effects in subsequent grades, with achievement gains of children during a given grade being higher if the entering skills of their peers in the same class are higher.
Peer effects make intuitive sense. If my child’s peers have better cognitive skills, the teacher doesn’t need to spend as much time remediating these peers’ skills, and can spend more time enhancing my child’s skills. If my child’s peers have better social skills and behavior, less class time is lost to classroom disruption, and my child will learn more. In addition, my child may directly learn better cognitive and social skills from his or her peers.
Peer effects provide an argument from enlightened self-interest for why all families with children in public school should support government efforts to broaden access to quality pre-K. Broader access to pre-K will improve overall achievement gains in the K-12 system.