Is it my grumpy post-holiday imagination or do adults seem to dress and behave more like children while the children dress and behave more like adults?
The reason I ask is because when term started last week I listened to a group of pupils talking about BBC1's Little Britain Christmas Special. They had evidently devoured every catchphrase and punchline and were now quacking them word-for-word in a giddy riot of laughter.
Suddenly a show that once felt like niche viewing for irony-aware adults feels shabby and sullied, its already precarious stereotypes and taboos too close to unthinking prejudice to leave us feeling comfortable. It's as if, like depleted uranium, the jokes have fallen into the wrong hands.
There's always a risk of old fogeyism in comments like this. I'm reminded of the complaint that "young people today think of nothing but themselves".
That was Peter the Hermit in 1274. So this isn't another of those rants about young people being superficial rude unimaginative surly add your own adjective here. Quite the reverse in fact: despite everything I read in the press about our supposedly Asbo-laden, tattoo-smothered youngsters, and after more than 20 years of working in schools, I continue to find them far more committed, lively, articulate and passionate about issues than I ever dared to be.
But the blurring of the boundaries between youth and adult life does make you sometimes wonder whether childhood is being squeezed out of their lives. Nowhere do we notice this more than in schools, where establishing clear boundaries between adult life and childhood is an essential part of the territory.
A long time ago, I think pupils saw me as a young teacher. I say "think"
because when I kicked off my career I consciously tried to look older than my 22 years. I grew an algae-like covering of patchy facial hair that I thought of as a beard. I wore aggressively-subtexted Doctor Marten shoes. I swaggered around corridors as if I was in charge.
Disconcertingly, a few weeks into my first post and in front of an English class, a pupil asked me how old I was. "Guess," I said. She peered at me for a moment. "Forty-five?" she said. I think I almost issued my first ever detention.
That early uncertainty about how far to "play the teacher" and how far to show that you're "in tune with the kids" is a kind of professional black ice at the start of our careers. We should avoid it at all costs.
One of the liberating parts of growing older in teaching is no longer feeling the need either to cling on to youthful street cred or to disguise your youth. You can - as far as we ever truly can - be yourself. I'm reminded of this if I hear trainee teachers refer to groups of students as "guys", or describe homework as "top", "sweet" or "dang" (OK, so I made that last one up).
I was inoculated in childhood against the temptation to use such teenage expressions. Only the trendiest, and therefore squarest, teachers spoke like that.
Like many of my contemporaries, I was nudged on to the moral high ground of dressing and speaking boringly after furtively watching early Grange Hill episodes. (I say "furtively" because my mother disapproved of the streetwise language ("flippin' 'eck, Tucker") and what she perceived as the racy storylines.) Grange Hill served as a kind of professional aversion therapy long before I contemplated becoming a teacher. Tucker, Zammo, Mrs McClusky, even the merciless Mr Bronson - they did me good, in the way that children's television in those days, like penicillin, was supposed to. Good schools have always recognised the importance of having a mix of ages among staff, with role models for students at both ends of the spectrum.
Such schools have also provided polite but clear mentoring of newcomers to the profession about the need to heed the dividing line between teacher and student, whatever our language and dress code.
There's something more important we do as well, and shouldn't in my opinion be embarrassed about: present our young people with values that take them beyond the cheap certainties of celebrity culture.
We must do this in the face of a popular culture that celebrates youth, indulgence and throwaway consumerism. We see the loss of traditional authority figures in young people's lives and a moral vacuum that clearly leaves some vulnerable pupils bewildered and exposed.
And that is why we should help them to understand that if we laugh at those larger-than-life outsiders portrayed in Little Britain, it's laughter of a specific and detached type.
Which is why perhaps one of the simplest things we can do as teachers and form tutors is simply have conversations with our pupils about the programmes they watch, and mediate a world they have stumbled into.
Geoff Barton is headteacher at King Edward VI school, Bury St Edmunds, Suffolk