"Whatchalookinat!" In my part of London that string of words usually means it's best to give a kind smile and a sensible response as you beat as hasty a retreat as you can manage, without looking too much like a potential victim.

So, it was with some caution that I turned round to see who had made this quizzical noise. Sure enough there was the usual spotty teenager in a hoodie with a gaggle of friends clustered round, all wearing challenging expressions.

"Watchalookinat! He said once more, slightly louder just in case I was hard of hearing. "It's a rare bird of prey, a peregrine falcon that lives wild in London. It's the world's fastest creature and you can see it, right there on the raised brickwork of the Tate Modern's chimney, just down from the top". I figured a fact-packed immediate response was probably the best response.

What happened next is a delight. It shatters all those preconceived impressions of teenagers held by anyone over the age of...cough; cough - OK, so I'm no longer the sprightly side of 30. The popular image of young people is one of mob driven, anti-social loudmouths that use aggression to mask inadequacies and to cope with unfamiliar circumstances. I know this is a gross generalisation but it is a popular image given life and reinforced by the diet of teen-vandalism and violence we're fed by our news providers. Just when I came to collude with this view, I can't recall, but I'm now appalled by my initial response.

The conversation continued in tongues. I made out "Letsavalook". The alpha male of the gang edged closer to the telescope and peered through, screwing up his face with one eye closed to see through the eyepiece. Next came a "Wow! It's amazin'. Ere, lookatdis". One by one, the gang ambled up to the telescope to look, delivering a barrage of questions. "Where did they come from? How big are they? What are they doing there? Are they a couple? Do they have children? What do they eat? Where do they live? How big are they?" My favourites were, "did you put them up there." And, "are they real"?

 The next fifteen to twenty minutes was spent chatting about the peregrines, life in Essex, how busy London is and how cute birds are. Our chat went on to include climate change and what the RSPB is doing to address some of the issues that will undoubtedly become the problems that these teenagers will have to manage in a decade or two.

At the end of this exchange, we parted company wiser and, I believe, each having learned something new. Making sense of the world around us is a universal goal and being outdoors is a good place to pursue it.