My husband and I used a 'Cinderella' rule to limit our kids' screen time. We don't regret it.

• Maria and Dexter Estrada locked their kids' devices at midnight with Google Family Link and Microsoft Family Safety.
• Emphasizing screen time moderation, the Estradas suspended this "Cinderella" rule on weekends.
• Both children excelled, winning $67,000 in science awards and pursuing tech and medical careers.

This as-told-to essay is based on a conversation with Maria Estrada, 51, who is a plant-science lecturer at Fresno State and the mother of two teenagers. It's been edited for length and clarity.

As a mom of two kids, I've struggled with screen time.

I didn't want my kids to be on the computer a lot. I've seen a lot of articles about kids being on computers, smartphones, and iPads.

Still, I believe in moderation. If you say no, it's giving them a signal that they cannot do it and that you are not respectful of their emotions, their needs, and their wants.

My husband and I are immigrant parents, so we are a little bit strict. We cannot tolerate some bad behaviors. For example, you need to be respectful with older people.

But we allow them to be kids, including online. My son loves video games, and they both watch YouTube.

I didn't want to just say no to their online activities, I don't want them to hate me, and I don't want them to feel controlled. And of course they used the internet on weeknights for their school assignments. But when they were in middle school and younger, we had a Cinderella thing: At midnight, all the wifi would disappear.

How we locked their devices at midnight

My husband, Dexter, used two different apps to lock our kids' devices so they couldn't stay up late texting, watching videos, and playing games. He used Google Family Link for their phones and Microsoft Family Safety for their computers.

Both apps allowed him to lock the kids' devices, though they could still receive calls and texts from the contacts we chose, such as ourselves. He could lock them out on a timer, so he set the lockout to go into effect at midnight and lift in the morning.

We also asked them to finish their school assignments before playing video games or watching YouTube on weeknights.

They got a break on the weekend. The midnight cutoff was lifted on Friday nights and reinstated Sunday nights.

Our son found a way around the internet block

When my son was in high school, he found a way to bypass the midnight block and connect to the internet. He's so honest that he told us he'd found a way and the trick wouldn't work anymore.

Uh oh, my husband and I thought. But we weren't mad. Our son had an innovative way of thinking. My husband said that if he can do that, it means he did his homework and found an out-of-the-box solution to his problem. I'm a scientist and my husband is a doctor, so we appreciate that.

We just told him he had to use the internet responsibly.

Our kids have both excelled

I don't do anything to restrict my kids' screen time anymore.

Pauline is 17 now. She's a competitive ballet dancer, and she wants to be a doctor and do medical research. She will put the phone down and say she's done. She knows how to police herself.

John is turning 20 this year, studying computer science at the University of California, Berkeley. He is not that good about the screens. I still have to remind him and ask him to stop browsing his phone. But sometimes when I see what he's doing, he's looking at the news.

Between the two of them, they've won more than $67,000 in awards for their science projects, which have used AI and robotics to address agriculture issues in plant science, like drought stress and pesticide-resistant super-weeds.

I wouldn't say that it totally worked, but the way they use the screens is responsible.