Which is more expensive - heating a school in Scotland, or cooling one in the Australian tropics? And which is less environmently damaging? For the past six years, Springburn Academy in Glasgow and Townsville High School in tropical North Queensland have been collaborating on a link which has so far seen two groups of Scottish young people travel Down Under, and three groups of Aussies make the return trip.
It's a project-based link which focuses on the impact of the environment on technology - and vice-versa - and grew out of Springburn's prize-winning after-school junior engineers and technologists club (JETs).
For 18 months, 16 to 18-year-old JETs and their Queensland opposites researched the energy used by their two schools, the sources of that energy and its impact on CO2 emissions. The Australians' trip to Glasgow offered a chance to compare notes and check they were both on the same track, before reaching their conclusions during Springburn's return visit Down Under.
The results were illuminating. Townsville, with its air conditioning, used marginally less energy than Springburn, with its heating costs alongside the usual computers, lighting, and other equipment. But when that energy was measured in terms of the CO2 it released into the atmosphere, Townsville's contribution to global warming was more than to double that of Springburn. The reason, students found, lay in the sources of that energy.
Much of the Scottish school's power came from wind, hydro-electric and nuclear power. Townsville, by contrast, used coal from open cast mining.
The sustainability project is typical of Springburn technology teacher Jimmy Johnston's approach to his subject, which focuses more on environmental factors than the usual aesthetics or cost. It also illustrates his determination to widen the horizons of his students and boost their self-confidence in an area where many have limited aspirations.
Johnston, Springburn's principal teacher of technical education, has long pursued an energetic programme of entering JETs for any design competition going - often successfully. The exchanges are the next step.
"It's a constant battle to get kids to believe in their potential," he says of his students, who come from tough housing estates in the north of Glasgow. "But if you can get them involved in a competition, or take them away to the US or Australia, they realise they are as good as anybody else - if not better."
It's a view echoed by Dale Collins, head of science at Townsville High, which also has partner schools in Kent and Japan. "The great thing about the students going over there is they see the kids are no different. It gives them a world view and makes the world smaller for them."
Cost and distance prevent frequent exchanges between the schools, so Johnston and Collins have based the link around long-term extra-curricular projects, taking in one visit each way by each school. They plan it jointly, keeping in touch with weekly emails, while students are in contact roughly once a month between visits.
Johnston - who collected an MBE this week for services to education - decided to make JETs international after seeing language and art teachers getting all the good trips. Initial links involved schools in the US. But although the Americans were hospitable hosts, they proved reluctant to leave home themselves. That wasn't good enough for Johnston who wanted an equal partner.
He found one in 1998 when a visiting Townsville teacher contacted the Smallpeice Trust, a UK charity which promotes engineering among young people. Springburn regularly sends students on its residential courses, and the two schools were put in touch.
Hot and humid Townsville, circled by rainforest, was founded by a Scot, but otherwise seems an unlikely twin. Its population is less than 100,000 (greater Glasgow's is closer to a million), lies hundreds of kilometres from the next big town and its sticky summers reach 40 LESS THAN C at a time of year when Glasgow is shivering at anything down to minus 20 LESS THAN C.
But while north Queensland is famous for its rainforests, resorts, islands and reef, Townsville is dominated by manufacturing, industry and government. "It's not highly commercialised," Collins says. "In some respects it's very like Glasgow." Townsville High is also a centre of excellence for maths, science and technology.
The first exchanges, structured around work experience placements, took place in 20002001. Since then they have focused on project work. They could be done remotely, but Johnston says the face-to-face element is an essential part. The curse of communications technology, he says, is that it doesn't foster interpersonal skills.
The trips are, as Australians would say, full on. Around a dozen Springburn students make the trip, packing in presentations, educational tours, civic receptions, and an exhausting schedule of social events alongside their project work. And they reciprocate fully when the Aussies come to Scotland.
They come away with an insight into how another society operates - similar to ours, yet quite different in subtle ways - and the ways people adapt to their environment.
The exchanges also foster an important sense of responsibility. Students do much of the organising themselves and JETs has its own international secretary. The cost per person is around pound;1,500, but intensive lobbying by JETs of Commonwealth programmes, public authorities and educational charities means students have to find only around pound;350 from their own pockets.
Students themselves talk of the difference it has made. David Logan, 21, now a final year design student at Glasgow University, was on the first trip to Townsville. "The type of area I grew up in, you think you'll never have a big ambition. You think you'll leave school early, get an apprenticeship and that's it. There are people I went to school with that still don't have jobs," he says. "But of the ones that were involved in JETs, one's doing quantity surveying, another is doing law - we all went on to that level. If it hadn't been for Townsville we wouldn't have realised we could do this."
The big lesson he took from the trip, he says, was that there are always different ways of doing things. He spent a week at Townsville Council's design department. "They were wandering around in casual clothes and they were really laid back. But they still got on with their work, and did it to as good a level as someone in a suit."
The next project offers another geographical angle and promises to be equally enjoyable, looking at how modern technology can gather data in inhospitable environments. Johnston is hoping to get his hands on a remote operated vehicle for some deep sea exploration - "I've got a couple of contacts in the North Sea" - while the volcanic craters around Townsville offer plenty of potential and a nice contrast. Exchanges are planned for 2006.
* The Smallpeice Trust
Tel: 01926 333200