Red Nose Day has capered and gone. And you’d need a heart of hessian to be unmoved by the sight of a whole building full of kids dressed up as Buzz Lightyear and Elsa from Frozen (which produces legions of small girls who look uncannily like Lady Gaga), all chipping in loose change so they can sweat uncomfortably in their costumes for seven hours.

And a special salute, in fact a Purple Heart, to those teachers who have the balls to join in. If you’ve never seen a head of year giving the full hairdryer treatment to a class of unpenitents while dressed as Russell Brand, then I suggest your bucket list could use an annexe. I used to wait tables in theme restaurants where it was practically considered part of your contract to wear the full Vegas Elvis ensemble three times a month, so I know how it feels. Reader, there are few pockets on a rhinestone jumpsuit. Or zips.

Schools can be like villages: to see so many people all pointing the same way, all joining in for the good of others on the opposite side of the planet, is undeniably heart-warming. It’s as close to pure altruism as we can find. And as an exercise in demonstrating - and encouraging - compassion, it’s superb.

There is, however, a tightrope to walk, even in what appears to be something so uncommonly lovely. I’ve seen schools where non-uniform capers are an excuse for the student community to dress as though the invitation read “gangsters and hookers”, where boys barrel up in FTP T-shirts (google “FTP police”), or belt buckles that inform us of what does and doesn’t taste like chicken; where Year 7 girls slither in having first walked slowly through the make-up car wash and spend the rest of the day proving that Girls’ Worlds were a chilling prophecy rather than a gruesome toy from the 1970s.

I can only assume their parents find the way to their remote controls with the aid of a Labrador. I’ve nothing against the odd dress-up day, but there’s a reason why schools have a uniform: because they’re meant to be safe spaces as free as possible from the inequities of class and wealth. Places where children are, for the most part, allowed to be children, not prematurely sexualised mannequins. If you heard about the mother who recently allowed her child to go to school as Christian Grey - complete with cable ties - then you’ll understand why my face is covered with palm-sized bruises.

And a word of warning for schools that encourage staff to join in with the japes: if the school community is broadly calm and staff enjoy a healthy relationship with the student body, it can be a wonderful exercise in humour and warmth. But if relations are fraught, be wise. I’ve seen schools where all staff had to dress up, or take part in “pie the teacher” gigs, excused on the grounds that it’s for charidee. That’s great if you’re powerful and loved. But if you’re new, or having a hard time with your classes, it can be a horrendous vehicle for legitimised bullying. Schools must always consider how decisions will affect the least powerful.

Pie the inspector, anyone?

Tom Bennett teaches at the Jo Richardson Community School in Essex and is director of the ResearchED conference