Wildlife presenter Steve Backshall said getting children connected with nature was "critical", as he opened a new "forest school" in Northamptonshire.
Cogenhoe Primary School invited the TV star to open its site while in the county for his live show on marine life at Northampton's Royal and Derngate.
Charley Oldham, head teacher, said she "couldn't believe" it when the VIP guest responded "straight away".
Backshall spent the day being shown around the new outdoor classroom.
The forest school includes a bug hotel and areas for meditation, storytelling and construction.
He said: "That's one of the good things about forest school. It's practical, it's real, it's there in front of you."
The primary school spent the day learning about the planet and sustainability, as part of their "Cogenhoe Goes Wild" day.
Mrs Oldham said: "Something we are so passionate about is creating that lifelong love of natural spaces and nature, and how we respect our world and everything within it.
"For me, I think more so now than ever, children need the opportunity to take risks but in a safer environment to build their confidence, their independence, their resilience."
While Backshall is usually seen on BBC show Deadly 60 dealing with dangerous animals, he helped the pupils with something much more relaxing - cooking marshmallows over a campfire.
He said: "I think it's really critical for us to be connecting young people to nature as young as possible and making it fun, making it cool, giving us ways that we can all get mud under our fingernails and feel nature in a really tangible way, and that's exactly what this forest school does."