Some say the devil’s greatest trick was convincing the world he doesn’t exist. I say it was convincing parents that computers can be educational.

I learned this the hard way over Christmas when my wife and I, stumped about what to get our middle school-aged son, decided to buy him a Kindle. A gadget that encourages him to read books? What could be better?

Well, we decided to go the extra mile by getting a Kindle Fire, and there’s a lot more to this device than black and white text. It lets you surf the Web, play movies and video games, and basically do anything you can do on an iPad or Nexus. Forget books — our boy was playing “Subway Surfers” approximately five seconds after unwrapping the gizmo.

It felt like a definite parenting fail, but as I thought it over, I wondered if my wife and I had inadvertently done something smart.

That’s because parents are always expected to be the guardians of screen time, limiting their kids’ exposure and taking it away before it becomes compulsive. I agree with that approach and have tried to follow it myself, but I’ve come to recognize that it has one real drawback:

If parents always control screen time, what happens when a kid has to control himself?

There’s no doubt that this is a difficult job, as anyone with a smartphone or cable modem can attest. Some psychiatrists classify Internet addiction as a genuine mental disorder, and in what strikes me as a clear sign of guilt, some tech gurus responsible for popularizing Web gadgets ban them from their own homes.

That might be possible if you’re a Silicon Valley billionaire, but the rest of us aren’t so lucky. More and more adults have nighttime work they’re expected to do at home, and that requires a computer. More and more kids have school-issued tablets and laptops on which they must read assignments and complete homework.

It takes the discipline of a Shaolin monk not to turn work time into play time, and plenty of adults regularly flunk that test. Soon enough our kids will have to fight that battle alone, so doesn’t it make sense that they get should get some early practice?

Dr. Jane Nelsen, a psychologist and author — she wrote the “Positive Discipline” book series — partially agreed with that premise but said children need help to self-regulate. She recommends holding a family meeting to discuss the need for limits, establishing a “parking lot” for devices and keeping them out of bedrooms so they don’t inhibit sleep.

Sounds good. Routines like that will help our kids build the digital fortitude they need, right?

Sure. Probably. Maybe.

“Pretty soon everyone will be addicted,” Nelsen said wearily, noting her own issues with turning off computer games. “We all probably already are.”

Nonetheless, she said, it’s important to set guidelines if kids are to have any chance at all as the digital current becomes ever stronger.

“Screens are here to stay, so we’ve got to figure out how to work with them,” she said.

One of the best ideas I’ve heard came from a blogger who goes by “Narrowback Slacker.” She wrote earlier this year that she lets her children have unlimited screen time as long as they first complete their daily tasks — a list that includes not just chores and homework but doing “something creative, active or productive for at least 45 minutes.”

She found that once her kids were engaged in non-screen activities, momentum tended to take over.

“Homework was suddenly getting done without me nagging,” she wrote. “Brownies were baked. Rooms were tidy. And computer time, while still substantial, was contracting.”

My wife and I have decided to try this approach, though I’m already anticipating complications galore. Does reading comic books count as productive? And what about building a fortress in Minecraft? Isn’t that creative?

Undoubtedly there will be plenty of cheating and backsliding, and I think my kids’ digital appetite will remain quite hearty. I’ll be shocked if they develop any hobbies that don’t involve pixels, but weirder things have happened.

I mean, my son has now actually read a book on his Kindle Fire. Who would have predicted that?