The number of teachers being trained to educate children outdoors has gone "through the roof" because of Covid-19, Natural Resources Wales (NRW) has said.
About 450 teachers have enrolled on its outdoor learning courses in the last two months - compared to 350 for the whole of last year.
The courses recently re-started following Covid restrictions.
They are delivered via Zoom and encourage teachers to use nature to help teach key subjects.
The rise follows a warning by the Institute for Outdoor Learning that a lack of school trips during the pandemic has cost the outdoor education sector £500m and caused the loss of 6,000 jobs.
Ffion Hughes, NRW education, learning and skills advisor, said outdoor settings could provide "endless" learning opportunities, from counting trees for maths skills, creating "woodland symphonies" with leaves and sticks for music, as well as teaching drama outdoors.
She added: "It's much more relaxing for both the teachers and children.
"There's plenty of space to socially-distance and room for children to have real-life memorable experiences without being stuck in a classroom, and masks, and feeling under pressure.
"For some, they have been outdoor learning for a long time, but Covid has given a new push and a new emphasis, and there's new motivation and enthusiasm for learning outdoors.
"So we really hope, as things settle down, this will continue and those that have been inspired will continue on their learning journey and continue to spend more time outdoors.
"Training-wise, our numbers have gone through the roof."
Rebecca Shone, a Year 2 teacher at Sychdyn Primary School, in Sychdyn, near Mold, Flintshire, said the outdoor learning is significantly helping her adjust to a new way of teaching.
"School life has changed dramatically and classroom teaching can be quite stressful with masks and social distancing," she said.
"Delivering lessons in the open air is far easier and more enjoyable and offers a nicer environment to engage the children.
"I try to take the class outdoors as much as possible, whatever the weather. We learn a whole range of subjects, from maths and science to language and art.
"Every Friday, we use woodland opposite the school for story reading, den building and drama.
"The children absolutely love it, and I can see the huge difference it makes in terms of how they interact during the lessons. There's also a big improvement in team-working, problem-solving and communication skills when we go outside.
"I've always been a huge fan of being outdoors, so being able to teach in the open air makes my job even better. It's definitely helped boost my morale and motivation over the past few months."
Pre-school children are also being taught in the natural environment.
Seventeen of those who attend Cylch Meithrin Sarnau and Llandderfel near Bala, Gwynedd, spend every session exploring and learning in and about nature.
Leader, Lisa Jones, said being outdoors was a "great way to engage children in early years education".
She added: "We do all kinds of activities - from painting and creating patterns with leaves, to treasure hunts using letters and numbers.
"There are so many brilliant ideas, courses and resources out there to help with planning the sessions and keeping them varied.
"The kids love being outdoors, and the parents are very supportive of our approach. It does help that we have a good stock of waterproof clothing too.
"Introducing youngsters to the natural world at a young age puts them in good stead to become environmentally responsible in the future."