When it comes to raising kids, you can't pass on what you don't have. That's true of family heirlooms and genetic traits, but it's also generally true of behaviors. Jump up and down about the value of reading all day, but if your kids never see you with a book in your hands, your effort is likely to be in vain.

The same can be said of our relationships to our screens, points out computer scientist and author of the new book, Digital Minimalism, Cal Newport, on his blog recently.

"If you carry your phone with you at all times, checking it constantly, it's difficult to convince your kids not to do the same, no matter how many rules you set or warnings you deliver," he writes before profiling parents who have chucked their smartphones entirely in order to set a better example for their kids (this isn't as extreme as you might think).

If you'd like to model a healthier relationship with your gadgets for your kids but you're unwilling or unable to do anything quite so radical, what's the solution? Newport offers a simple yet effective suggestion.

Why it's worth going to the trouble

Before I pass on Newport's advice, it's worth briefly underlining why instituting a well thought out family policy on tech use is worthwhile in the first place. Researchers are still arguing about how much impact screen time is having on kids' mental health, but a few things are clear. First, kids themselves say they want help from their parents with setting healthy boundaries when it comes to screen time.

And two, excessive phone use has been linked to loneliness, lower quality relationships, and even less smiling among adults. If your kid becomes a screen addict now, they're highly likely to stay one in as they grow up as experience these negative effects. 

How to encourage your kid to have a healthy relationship to tech

So say I've convinced you that helping your kids develop a thoughtful relationship with their gadgets is a good idea. How do you go about it? Following in the footsteps of tech icons like Steve Jobs and Bill Gates, your first impulse might be to set strict rules around screens. But studies show this approach can backfire badly when overprotected kids go off to college and discover they don't have the tools or willpower to set their own boundaries.

Newport thinks he's found a better way, rooted in the principle that the best way to teach is to show, not tell. He calls it the "foyer phone method." Here's how it works:

In the evening, after work, you leave your phone in the foyer by the front door [or whatever out-of-the-way spot your home offers] with your keys and wallet. If you need to look something up, you go to the foyer to use the phone. If you're expecting a call or text message that you need to answer, you put on the ringer, and if it rings, you go to the foyer. If you're bored during a commercial while watching TV, then you're just bored.

This has the advantage of effectiveness ("your interactions with your family become screen-free by default," Newport stresses), simplicity and finally subtlety, which as any parent of a teen can tell you, often works better than hectoring. But it also has another important benefit for parents -- it gently forces you to acknowledge just how big a roll phones were playing in your family life in the first place.  

The foyer phone method means you "avoid the micro-glances at your device as you go about your household business -- glances you think are surreptitious, but that your kids are almost certainly taking note of and internalizing as a model of the phone's importance," he explains.

It's a double win. Not only does it help you keep your own worst impulses around tech in check, but it also communicates to your kids an essential lesson: phones are tools for specific purposes not a constant source of distraction and shallow validation. 

What's your approach to helping your kids set healthy boundaries with their devices?