Inveraray Primary is in a lovely location, down the old carriage drive from the castle and overlooking Loch Fyne. However, the sudden downpour that pelts the playground, forcing pupils and teachers to flee for cover, vividly illustrates the point being made by headteacher Anne Paterson.
"To use the playground regularly for lessons takes planning and flexibility. You can't trust the weather."
This was one reason some people took a little persuading when she conceived her plan five years ago of making lessons active and outdoors, not just occasionally, but whenever possible. "Some days nobody is in the building at all," Ms Paterson says.
"It began with a project on tree-dressing that I organised not long after being appointed. The children loved it."
"They told me they wanted to go outdoors more often for lessons."
As the clouds blow over, children re-emerge cautiously to resume their activities. For some, this seems to consist of a great deal of running around.
"This is a game called Monkey Run that we invented ourselves," says young Fiona.
The basic idea of the P4P5 project on inventors is to make up and test new playground games, explains Ms Paterson.
"With every project we look for ways of getting kids outside. Here they're learning about invention."
While Fiona says she enjoys being in the fresh air for lessons, her friend Grant is, if anything, more enthusiastic. "It's much better than being in a classroom. You don't have to sit at tables."
Two other classes outside are the P3s, who are working on a castles project, and the infants, who are practising arithmetic.
The intrepid P3 teacher, Linda Leyland, is holding rubber rings at the end of outstretched arms while the children, carrying colourful shields, try to capture them with cardboard lances.
"It's called jousting," the excited youngsters explain. "If we had horses, we would try to knock each other off them."
Ms Leyland says the pupils love going outside and learn better. "We have been doing their maths tables recently using a game called Sharks. They learn them so much quicker when they are outside running about than if they are in the classroom."
Nearby, the infants' teacher calls out: "What is five add on five?" The little ones mill around, gradually accumulating on the large "10" chalked on the ground.
Outdoor lessons have improved behaviour and motivation among the children, particularly the boys, for whom inactivity is a struggle, says Ms Paterson, and raised attainment. "Being active gives them a bit more thinking time," she says.
"Our maths and reading were always on a par but this year the maths - a focus for outdoor lessons - is up 5 per cent. We are convinced it is because of our active approach and because the pupils see the subject in context."
Other subjects also escape the confines of the classrooms. Science classes visit the wildlife pond and wilderness area, social subjects and healthy eating lessons take place in the garden plots and polytunnel, while language and literacy classes meet in the outdoor classroom with its wooden stumps for the children and magnificent storyteller's chair.
"A project with the Lighthouse, Glasgow's centre for design and architecture, gave us one chair design that was so wonderful we decided to have it made," says Ms Paterson. A local company that had previously produced the school's elegant buddy bench, shaped like outspread wings, was commissioned to produce the huge chair that can seat three children or one large Highland storyteller in full regalia, she explains.
Sustaining support for such a change in pedagogy demands good communications, particularly with parents, says Ms Paterson. "We have had a lot of good feedback from parents, who like what we're doing and notice the difference in their kids.
"So often teaching initiatives start off well, then fade away. I think that happens for two reasons: they haven't got into the core curriculum and they haven't involved parents and the whole community."