Back when I was a first-time mom who knew everything about stellar parenting (yes, I’ll wait while your eyes finish rolling), I was sure my son didn’t need preschool. I mean, what could he possibly learn there that he didn’t already know? At 4 years old, he was able to read anything on his bookshelf. He knew all his shapes. He knew all his colors. He could count as high as anybody asked him to. I stayed at home with him and enriched his little brain with developmentally appropriate activities whenever I could. He would be bored if I sent him to preschool, I reasoned.

So I didn’t.

When he was 5 and eligible to start kindergarten, I didn’t even consider waiting another year. He was totally ready! On the first day, I took him into the elementary school gymnasium where all the other carefully combed, wide-eyed kindergartners were sitting in a group. I watched from the sidelines as they all took in their new surroundings, fidgeting nervously.

Finally it was time for them to head to their respective classrooms. My son’s new teacher said, “Okay, kindergarten! Let’s get in a line!” One by one, they lined up like ducklings — except for my son. He stood beside one of his classmates, shoulder to shoulder, oblivious to what he was supposed to do. And as I watched his teacher gently guide him to the back of the line, a flood of panic washed over me, and I came to a guilty realization: My child didn’t even know how to line up. He’d never had to. No daycare, no preschool, no siblings (at that point anyway), no reason to wait his turn.

I thought he didn’t need preschool since he already knew more than the fundamentals of language and math. But it had never occurred to me that by missing out on preschool, he had missed out on so much more. Namely, the opportunity to socialize and learn the basics of being part of a class — critical skills he would need as he went through the next 12 years of school. I naively thought my son would start school ahead of the curve, but in many ways, he was far behind the other kids.

I learned the hard way, so you don’t have to, because here’s the thing: Whether your 3- or 4-year-old is a budding calculus whiz or can barely string sentences together, preschool is a valuable resource that equips them with the sturdiest educational foundation possible. This isn’t just an opinion. It’s recently been verified — and not for the first time — in a report authored by a plethora of early childhood professionals from prestigious institutions such as Duke, Vanderbilt, Rutgers, and Harvard, just to name a few. They found that preschoolers show significantly higher levels of kindergarten-readiness than their non-attending counterparts. Researchers also determined it’s extra-beneficial for kids from low-income families and multilingual households.

Yeah, your child will be taught basic things like colors and shapes and sometimes things they’ve already mastered. But the benefits they take away from preschool go much deeper than memorizing their letters and reciting songs.

Preschool helps your child feel secure. It’s a stable, nurturing environment where kids see the same faces, stick to a similar routine every day, and know that their teacher cares for them. Not only that, but it also helps reaffirm that when you go away, you always come back.

Preschool provides diversity. What do kids of different ethnicities and social and cultural backgrounds have in common? At preschool, they get to find out — and learn that they can be friends with all types of people.

Preschool teaches responsibility. Preschoolers are expected to hang up their coats and backpacks, keep their desks clean, pick up their toys, and often have classroom “jobs” like turning off the lights on the way to recess.

Preschool promotes self-sufficiency. In a typically sized classroom, teachers don’t have time to wipe every nose, wash every hand, zip every coat, and clean every butt — which leads kids to learn to do these things (and more) on their own.

Preschool emphasizes good manners. Kids practice waiting patiently for their turn, sharing toys and art supplies, saying “please” and “thank you,” speaking in an inside voice, and generally being polite human beings.

Preschool keeps kids active. Physical play is a huge part of preschool — not just on playground equipment, but through dance and games involving movement as well.

Preschool allows imagination to flourish. Most preschool classrooms are a treasure trove of opportunity for imaginative play. There are blocks to build with, art supplies to create with, and costumes and props so kids can pretend to be parents, doctors, rescue workers, or whatever else they can come up with.

I thought I was giving my son all he needed at home, but as it turned out, there are benefits to attending preschool that even the most involved, well-intentioned parent can’t provide. I learned from my mistake though, and sent my younger kids who reaped the benefits and showed much more readiness for school than their older brother.

As for my oldest, preschool-less son, I feel bad that he missed out because of my ignorance. But hey, I guess someone’s got to be the guinea pig.

Rita Templeton

@fightingfrumpy