There’s a particular kind of energy that comes with having a 4 or 5 year old. They are funny and opinionated and full of questions you don’t always know how to answer. They have best friends and favorite colors and strong feelings about what goes on their plate. They feel, in so many ways, like a real person. That’s because they are!
What parents often don’t realize is that underneath all of that personality, something extraordinary is still happening. Their brain is in one of the most significant developmental windows of their entire life.
We think every family deserves to understand what that means.
The Brain at 4 and 5: What Is Actually Happening
By age 3, a child’s brain has already reached about 80% of its adult size, but the work is far from finished. The years between 4 and 5 are when the brain is doing some of its most sophisticated wiring. Research specifically identifies the 4 to 5 year old age range as a cornerstone period for executive function development: the cluster of cognitive skills that includes working memory, inhibitory control, and cognitive flexibility.
Why does that matter? Because working memory at age 5 has been shown to be a stronger predictor of academic performance six years later than IQ. Not what a child knows at 5. How their brain is organized at 5. Executive function is not built through worksheets or flashcards. It is built through play, through meaningful relationships, and through environments that invite children to think, investigate, and problem-solve on their own terms.
What Play Actually Does at This Age
Research published in the International Journal of Early Childhood found that role play and play with rules produced sustainable, long-term improvements in executive function in preschoolers, with effects that held four months after the interventions ended. A separate study found that children in play-based experimental groups showed significantly improved executive function performance compared to those in more structured settings, reaffirming what Reggio Emilia educators have known for decades.
This is not the easy path. It is the right one. It takes genuine skill for an educator to design an environment that builds these capacities without direct instruction. But the outcomes speak for themselves.
What Kindergarten Teachers Actually Want
Most parents spend the years before kindergarten worried about letters, numbers, and writing their name. But what kindergarten teachers consistently say they want children to arrive knowing has very little to do with academic content. They want children who can follow multi-step directions, manage frustration, listen to a peer, and approach something new with curiosity rather than shutdown.
These are exactly the skills that ages 4 and 5 are primed to build and exactly the skills that play-based environments are designed to develop.
The Reggio Emilia Difference
The most compelling evidence for what quality early childhood education at this age can do comes from a landmark study published by the National Bureau of Economic Research and available through the National Institutes of Health. Researchers tracked individuals across five age cohorts who had attended Reggio Emilia-inspired preschools (some of them as far back as the 1950s) and compared their outcomes to those who attended other programs or no preschool at all.
The findings were striking. Relative to receiving no formal care, the Reggio Emilia approach significantly boosted outcomes related to employment, social-emotional skills, high school graduation, and civic participation, outcomes that showed up decades after those early years ended.
A follow-up study published in the Journal of School Psychology found that children in Reggio-inspired preschools, including those considered at risk due to lower socioeconomic status or language challenges, showed trajectories of school adjustment that were largely indistinguishable from the broader population. The quality of the environment leveled the playing field in ways that lasted.
What This Means for Your Family
If your child is 4 or 5, you are in one of the most significant windows of their entire development. The environment they are in right now, the relationships they are building, and the way their curiosity is being met every morning is all shaping who they are becoming in ways that will carry forward for decades.
