It all started years ago, when I first learned my wife and I were going to be parents: I began collecting science-based parenting advice, both here on Inc.com and in my continuously updated (free) e-book, How to Raise Successful Kids, now in its 7th edition.

Here are seven of the most interesting and useful studies that I've found, along with the habits they find successful parents often practice:

1.    Teach kids to take pride in their effort, not their gifts.

Of all the advice I've shared over the years, this is the habit that prompts the most replies -- not from parents who don't think it works, but from adults who realize how much sense it makes, and how much they wished their parents had practiced it.

Bottom line: Don't praise your kids for their gifts. Praise them instead for their efforts.

In other words, not this: "Sally, you're so good at math!" Or else, "Ethan, you're such a fast runner!"

Instead: "I'm proud of how hard you studied!" Or: "I could see the determination on your face as you crossed the finish line!"

There's a whole line of scientific studies that backs this up, largely stemming from the work of Stanford University's Carol Dweck. But, I was also pleasantly surprised to learn recently that of all people, it's also one of the top bits of advice that Jeff Bezos preaches to young people and their parents.

2.    Get them to play outside.

Actually, it's not only kids who should get outside and play; adults like you should too, according to science. But let's focus on the kids.

Studies show that younger kids whose schools don't include outdoor recess during the day had a harder time developing good reading skills. (The results were more pronounced in boys, but it mattered for girls, too.)

And, more recently, researchers from North Carolina State University said they found a striking correlation in kids aged 10 to 18, regarding how much time they spent outdoors and their emotional well-being.

Interesting note: This study was from last year, and it's a good example of one of the scientific silver linings we'll see as a result of the pandemic: lots of chances to study and measure things for which it would have been hard to find subjects previously.

(Super-striking data point, from my point of view: "About 60 percent of teens said they were able to get outside once a week or less," during the early months of the pandemic.)

3.    Make sure they learn about good role models.

Kids will rarely be what they cannot see.

Researchers at New York University, Princeton University, and the University of Illinois studied the degree to which boys and girls believed that grown men and women were likely to be "really, really smart" (their phrase).

At age 5, both boys and girls believed that grown men and grown women were equally likely to be "really, really smart." 

But by ages 7 and 8, girls had overwhelmingly grown to believe that men were more likely than women to be "really, really smart."

As they went through school, this incorrect belief led some girls to pursue less ambitious career goals than boys, and to avoid courses and careers in science, technology, engineering and math.

We should note that on average, girls actually get better grades than boys, have higher rates of graduation from high school. They also go on to college at higher rates. So, it's  a matter of perception being the exact opposite of reality.

There's a ton to unpack and remedy here, but we can point to two things:

First, the part above (#1) about praising kids for effort over gifts, and second, making an extra effort to ensure that both boys and girls have opportunities to see and study "really, really smart" women role models.

One last point here: As the father of a daughter, I see moms and dads who do in fact make women role models a priority for their girls. The slightly less obvious part? Make sure they're a priority for boys, too.

4.    Let them see when you fail.

Young kids sometimes seem to think their parents are gods. Honestly, let's admit it: it's not a totally unenjoyable experience.

But, let it go, because researchers at the Massachusetts Institute of Technology experimented with children as young as 15 months old, and found that the less their parents allowed them to see how much they struggled and failed at times, the less resilient their kids were.

What I found most amusing about this study is that it suggests you should struggle in front of your kids and show how incomplete your work can be--and then, the study authors themselves struggled to define it, and seemed very aware of the incompleteness of their work.

"There's some pressure on parents to make everything look easy and not get frustrated in front of their children," Laura Schulz, a professor of cognitive science at MIT, said in a press release. "There's nothing you can learn from a laboratory study that directly applies to parenting, but this does at least suggest that it may not be a bad thing to show your children that you are working hard to achieve your goals."

5.    Do this with their toys.

This one fascinated me: Researchers at the University of Toledo studied how young kids played with toys.  

To cut to the chase, they found that kids who were given a smaller number of toys to play with found ways to expand their imaginations and  use them more creatively than kids who were given larger numbers of toys.

So, don't get your kids so many toys? Is that the advice? (I can hear the rumbling of millions of kids rising up in righteous anger over this one.)

No, not really. Instead, the idea is, especially with younger children, to rotate their toys, and design play spaces that encourage them to focus on the toys they're playing with, rather than being distracted by other options.

It reminds me of a lesson I've learned in marketing: People love choices but they hate decisions. It sort of applies to young kids, too.

This also provides a little bit of backup to a parenting truth we all learn very quickly:

Often, the more a kid insists that he or she absolutely, positively, must have one specific toy, the more likely it is to wind up gathering dust before long in the corner.

6.    Limit their screen time to this many hours.

Is there a more contentious issue regarding kids in the 2020s than screen time?

Our parents didn't know how good they had it, when they could tell us to go outside and play (see #2 above), without worrying that we'd bring tiny screens with access to basically the world's entire output of entertainment and information.

Now, it would be counterproductive and probably impossible to try to limit kids' screen time entirely. (Also, hypocritical, since I wrote this on a device with a screen, and you're reading it on one.)

And, I could write an entire column on how much screen time kids should have. (Oh wait, I have written one).

But to summarize, researchers from San Diego State University and the University of Georgia combined a series of previous data sets to find the sweet spot of realistic digital use: between 1 and 2 hours a day.

We should also add a trend that the researchers found: It's that measured happiness and well-being among kids in middle school and high school has steadily declined since about 2012.  

What happened around 2012? That's basically the rough point when U.S. kids started to get their own smartphones, along with unlimited data plans. 

7.    Stay close, but not too close.

Speaking of sweet spots (and we were, in the last section), the last habit to include in today's installment has to do with hovering. 

We have two main sources to draw on here. First, the experience of Julie Lythcott-Haims, the former dean of freshmen at Stanford University, who has described helicopter parenting as one of the scourge of successful kids. 

I'm summarizing of course -- she has a whole book on the subject, called How to Raise an Adult -- but her overall lessons learned include things like letting kids try things and fail, making sure you don't get so invested that you wind up fighting all their battles for them, and the like.

That's good advice. But I want to mention it in the context of a survey of other studies that showed, basically: When in doubt? Run to their side.

Granted, these two conclusions conflict to some degree. But, if there's one thing I know you already know as a parent: Nobody ever said this would be easy. The fact that you've read this far tells me you're on a road to figuring it out. 

(Don't forget the free ebook: How to Raise Successful Kids.)