The fact that I lived in Canada also helped: there were lots of forests to soak up the carbon dioxide from my gently-used car, and not that many people around to create waste and smog. In fact, if you took the entire population of my city and put them in a room, I’m sure it would be no more crowded than the average Tesco on a Thursday evening.

Unfortunately, it turns out that I’m a wanton polluter and consumer. I’ve discovered a website that calculates how many Earths would be needed if everyone in the world lived like me (www.mec.ca), and the answer is four.

Time, then, to drop the piety. I’m hardly an example to my students.

But neither is the school system itself. We try to teach about the environment and responsible consumption, yet we do it in an institution that, in so many ways, contributes to the problem. Straightforward examples are easy to think of. Look at the average school building, anywhere from Toronto to Tooting - it is old, badly insulated, and single-glazed. Nor do the thermostats work properly, so that sometimes in winter the heat is pumping but we have to open the windows regardless. There isn’t any money to fix the buildings, so we have to put up with it. When we try to compensate for the waste of energy by, say, cycling to school, there’s rarely a secure place to leave our bikes, so we take our cars instead.

Then there’s the cult of paper. Instead of writing assignments on the board, we run off 30 photocopies and hand them out (call it 60, because the first set usually comes out wrong). And we encourage our students to use word-processors but still want them to print out their work, so they use a pile of paper as well as a load of electricity. To help them, we buy new school computers as often as we can, throwing the old ones, full of mercury, into skips. And here in Ontario, we now have to staple an assessment rubric to every piece of work, perhaps encouraging my principal (in a school of 1,200) to reveal how many sheets of paper we used last year. The number was so staggering that my mind went blank, but it certainly ended in “million”. At least we recycle.

How many staffrooms are stocked with coffee that isn’t fairly traded? And how many school sports kits are made in sweatshops? And, most importantly, how many heads, by hiring overseas teachers from agencies, inadvertently damage the education of millions? Here in the west, our ongoing teacher shortage - and our inability to deal with it by attracting new blood to the profession - is having a devastating effect on developing countries. South Africa, for example, is haemorrhaging thousands of teachers to recruitment agencies, in addition to more than 70,000 who will die from Aids by 2010.

Meanwhile, the poaching of Jamaica’s teachers is putting the island’s future at risk. According to a conservative VSO estimate, Britain alone takes 1,000 teachers per year from developing countries, many of which face a pupil:teacher ratio of 100 to one.

Despite this, we continue to tell our students to be responsible consumers.

Yet we will be hypocrites as long as we teach in schools that, often through no fault of their own, waste resources and poach teachers from places that cannot afford to lose them.

It is a situation that could easily change - but that, as usual, would require investment. Buildings need to be fixed, and schools need policies to eliminate waste. It’s all very well to bemoan the use of paper at the end of a year, but we need to be proactive in thinking of alternatives. We also have to make teaching a more attractive career - another expensive undertaking. Meanwhile, in the grand imperial tradition, we’re plundering the world to keep ourselves afloat. If we’re going to teach our children about citizenship, we should make sure we are up to the job. If I need four planets, how about the average school?

Nicholas Woolley teaches in Toronto, Canada