Mom and her kid have made it to the studio on time, all dressed in the “perfect outfit” for their portraits. As coats come off, bags are set aside and hair is smoothed, a nervous smile comes across Mom’s face, hoping we’ll be getting natural smiles from her kid. “He’s pretty fussy today,” she says. “I really hope you’ll be able to get just one decent photo of him. All the kids in your pictures have such great smiles on their faces…and I’m really just hoping we get one.” What Mom doesn’t know yet is that I’ve got a secret weapon in my back pocket that helps get natural smiles from kids every time that’s more effective than dancing, singing or any other kids portrait trick: bubbles. Lots and lots of bubbles.

I smile reassuringly and nod my head at her, knowing exactly what it’s like to schedule a photo session for your kids only to have them wake up in a bad mood on session day. “Don’t worry, I have no doubt that we’ll get at least a handful of good, natural smiles out of him today,” I reply. When you’re first starting out as a photographer, answering Mom with genuine reassurance that you can and will get natural smiles from kids can feel nerve-wracking. Can you really connect with every single kid that comes in front of your camera? What about the ones that are really, truly in a no-good-terrible-awful mood?

[Read: Creative Portraits That Explore Kids Natural Beauty and Imagination]

Over the years, you’ve probably developed your own set of tricks and tools to get great smiles out of kids, no matter their mood. Some photographers use toys that go around camera lenses, others make funny noises or wave favorite toys around. But what child isn’t absolutely mesmerized by bubbles? They’re simply magical. It doesn’t matter their age; small babies and 10-year-olds alike love bubbles.

I keep a bubble machine in my studio, just off my background and within easy reach of where I shoot from so that when the time comes, I can just reach over and flip it on. Moms and dads instantly make an “oooooh” noise and get excited. As the bubbles start to float towards them, tiny sitters and toddlers instinctively reach for them, trying to see what they are. Their little faces light up with complete, unfiltered joy as streams of bubbles float around them. Bigger kids will start jumping to try to catch them, wave their arms to move them around, or twirl in circles to have their very own bubble-filled dance party.

[Read: A Beginner’s Guide to Using Off-Camera Flash for Portraits]

Bubbles are one of a handful of things that can be added to a photo without taking away from the main subject of the photo at all. Plus, chasing and playing with bubbles gets all of the kids in front of my camera to relax and be natural, while all at the same time completely forgetting that there’s a camera in their faces.

[Read: Fine-Art School Portraits—The Beauty of Volume Photography]

I wind up getting so many more natural, fun, carefree photos of the kids that come into my studio—exactly the kind of photos that their parents are hoping to get “just one” of. These always become Mom and Dad’s favorite photos because they show the pure, unfiltered joy of what it means to be a child, something that every parent hopes to capture on camera of their children. In terms of my business, these are some of our most purchased images and likely result in a bigger sale as well.

After all, what parent can say no to a completely joyful, natural smile from their kid?

Kelli Wilke is a portrait photographer and co-founder of the Portrait Club, located in Wilmington, Delaware, and opening soon in Atlanta, Georgia.