They are in the back seat of the car singing something by Katy Perry. I don’t know the song. But they do. They know every word. They sing the way they run, the way they draw, the way they swing on the monkey bars, the way they dance and play and pretend, the way they do everything.

With energy and boundless joy.

They go from Katy Perry to “My Favorite Things’’ to “Five hundred twenty-five thousand, six hundred minutes.’’ They trill, they belt, they croon, giggling in between. They are 9 years old, “almost 10!’’ they say, almost double digits. Like so many other children, they are in a hurry to grow up, grown-up, to them, a magic kingdom which is all around them, which they see and hear and bump into every day, which intrigues them, but which they cannot enter. “When I grow up,’’ they say with stars in their already bright eyes. And then they list all the things that someday they will do and be. I’m going to be a dancer. I’m going to be on Broadway. I might be a writer or a lawyer or a teacher.

They dream of far grander days. The future glows brighter than the present. The road to being a grown-up dazzles with fun and excitement. When they’re 10, they can get their ears pierced. When they’re 11, they will be in sixth grade! When they’re 12, they will be almost 13!!

What they don’t know, what they can’t begin to imagine, is that little in their lives, no matter how long they live, will outshine this here and now.

I wish I could tell my grandchildren that now is the real magic kingdom. Singing in the back seat of a car, dancing in a living room, strutting down the steps in some put-together garment made of brocade and boa, clowning around, hamming it up for your parents and your grandparents and the people who love you, who watch and smile and take pictures and applaud.

These are the moments that, when you’re all grown-up and looking back, you will remember and long for.

I remember bouncing around in the back seat of my father’s car, pre-seat belt days, with my friend Janet Butler, the two of us singing all the way to Chicopee, a name we exaggerated and repeated over and over, Chic-o-PEE, until my mother told us to stop. Eighty miles of bumpy back roads. We giggled and sang the entire way, the radio turned down, my mother turned around, my father stealing glimpses of us in the rearview mirror, because we were the entertainment. Same thing every time Rosemary and I were together. We sang “Tammy’’ and “True Love’’ and “Turn Me Loose’’ by Fabian Forte, who was so famous he was known by only his first name. We would be famous someday, too. We put on talent shows. We hand-printed fliers to promote them. We turned my backyard patio into an outdoor stage.

My daughters did the same thing. Different songs. Different costumes. Different backyards. But the same boundless joy. Lauren and her best friend, Amy, poised at the top of the stairs, Lauren with pince-nez glasses, Amy with a May wreath in her hair, belting out some show tune. Julie and her best friend, Sarah, cartwheeling across the lawn, standing on their heads for a whole minute. Ice skating. Roller skating. Every day, a different show.

I look at my granddaughters and want to press pause. I love their little kid voices, their earnestness, the pride they take in the Legos they build and in the stories they write, in the lyrics they know. I love their genuineness, their glowing faces, their silliness.

I listen to them sing. I record them. I take pictures. Sometimes I videotape.

But I don’t need to because 9 is unforgettable. Because I will always remember these days.

Beverly Beckham’s column appears every two weeks. She can be reached at bevbeckham@gmail.com.