We live in a Cornish town with three beaches. There's a small park two minutes’ walk from home where neighbourhood children congregate, and a bigger park you could reach in 15 minutes on foot. The sun is shining, school is over, the day has plenty of daylight hours left in it, and there are many things the children could be doing to unwind.

"I want the iPad," says my eldest son, stomping in from secondary school.

"It’s not fair," complains my daughter. "He’s got the iPad."

"Can I have your computer?" asks the middle one. Inevitably, despite having beaches and parks and friends at their disposal, what my children want to do after school is pick up a screen – any screen – and stare at it like zombies. They are not even interesting zombies – they could certainly not summon the energy to find a human being and devour their brain. They just want to look at pixels and consume some media.

They are not alone. Today’s children spend an average of four and a half hours a day looking at screens, split between watching television and using the internet. Last year it was reported that a child born today will spend a quarter of its life staring, in a non-work-related way, at a screen. I recently taught a residential creative writing course for teenagers in Devon at a centre with no internet connection, and was struck by the teenager who yawned all morning on the first day, explaining his insomnia with the baffling claim that: "I can’t sleep without Wi-Fi." When you add in adult fears that our children will be abducted or run over, it becomes far easier to keep them inside where we can see them, and let them be passive, coddled, safe, on a sofa.

However, in the past few years a growing number of people and organisations have begun coming up with plans to counter this trend. A couple of years ago, film-maker David Bond realised that his children, then aged five and three, were fixated on screens and iPads to the point where he was able to say "chocolate" into his three year old son’s ear without getting a response. He realised that something needed to change, and, being a London media type, appointed himself "marketing director for Nature". He documented his journey as he set about treating nature as a brand to be marketed to young people. The result was a film called Project Wild Thing.

Bond has hit a nerve. "It is great," he says, "to have formed a rallying cry: children need to be outdoors more." His film charts the birth of the Wild Network, a group of organisations with the common goal of getting children out into nature. The network has grown exponentially, and now comprises over 1,500 organisations, from huge charities such as the National Trust and RSPB, to smaller mental health organisations, teachers’ groups, and pre-schools.

"It’s something we’ve been campaigning on for the past 100 years," says Jim Wardill, community team manager at the RSPB. "Environmental education work is a fundamental part of what the RSPB is and does. Over the past 10 years or so, people have realised that kids just aren’t getting out as much. It’s about the connection to nature, the emotional bond you develop with the outside world."

Helen Meech, Assistant Director of Outdoor and Nature Engagement for the National Trust, says: "Spending time in nature not only make kids happier and healthier human beings. People who spend more time outdoors as kids are the ones who have a stronger interest in environmental issues and protecting the planet. And it's great fun too!"

"For children, play and time outdoors can be particularly important, helping to build resilience as well as boosting wellbeing," says Chris Leaman, policy manager at the charity YoungMinds, which campaigns on issues surrounding children’s and adolescents’ mental health. Children can enjoy watching things on screens, but the things they remember are the adventures. Two years ago my two boys went off kayaking with their father, and slept on a stony beach that turned out to be covered in jumping insects. Although it sounds hellish to me, they still talk about it with astonishing enthusiasm.

Projects and campaigns include the National Trust’s 50 Things to do before you’re 11¾ list, the RSPB’s annual Big Wild Sleepout, and many other initiatives such as Play England’s campaign for parent-led street play.

David Bond says that in his experience it is actually as simple as getting a child outside. "Just five more minutes outdoors can make a difference," he says. "There is a lot of really interesting evidence which seems to be suggesting that if children are inspired up to age of seven then being outdoors will be a habit for life." His own children have got into the habit of playing outside now: "We just send them out into the garden and tell them not to come back in for a while."

It is easy to blame the media, the sell-offs of playing fields, town planning that does not incorporate play space for children, among other culprits. However, as David Bond says: "All those things make you, as a parent, less responsible. Don’t leave it to anyone else. It’s down to you."

The WildTime App, part of Project Wild Thing, offers a variety of ideas for outdoor activities: just choose a time period from 10 minutes to half a day, and it will throw up suggestions, from reading a book out of doors to building a den. A quick look at it, and I immediately decide we should grow some sunflowers in our tiny garden. The RSPB’s website also offers suggestions such as making homes for ladybirds and identifying animal tracks, among others. You can camp, go for walks, lift up logs and watch the creatures scuttling away.

I have recently started sending my younger children, aged 10 and seven, to the park around the corner without me. This was hard to do, at first: seven felt very young to be unsupervised and I initially felt like the most irresponsible parent in town. I stayed at home for as long as I could manage it, before walking as fast as I could to check on them. They were, of course, fine. They were, in fact, more than fine: they were relishing their independence, and were only pleased to see me because they wanted to take my phone in order to time their obstacle course.

Now they go there often, and I leave them to it for a while. They meet friends, and play and race and climb trees, and I try to manage the little voice inside me that calls me a bad parent. I can’t help, however, creeping along the road regularly to check. Amazingly enough, they are always not only all right, but laughing.

Summer is upon us. There is an amazing world out there, and it needs our children as much as they need it. Let us get them out and let them play.

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