Mr Lace, the teacher in Philip Ridley’s Krindlekrax bursts into tears at the mention of Shakespeare’s name. “Oh, the wonderful Bard! The Saint of Stratford! The emotion wells up in me. Down my heart! Down! Down!” I’m beginning to feel the same way.

Three rows back from the stage, hidden between a forest of long-legged students, I feel fairly safe from actors who might want to interact with me before the rest of the audience. I peer around the theatre, flick through the programme of As You Like it and then I see the dreaded reference to “gender issues”. Sure enough, the opening scene sees Celia kissing Rosalind on the upper thigh. It is going to be one of those nights.

Why is it that for so many directors Shakespeare has to shock? We bring along our eager classes, trained in the complexity of the plot, suspending disbelief in their youthful way, ready for their first dramatic experiences of wonder, and what do we get? A Caliban with an enormous scarlet phallus that bobs around so animatedly that it causes consternation on biological grounds. “It’s his dick,” I hear one of our 11-year-old girls whisper to another. Gales of laughter - a Tempest indeed. My resignation, or epitaph, is being written as the actors cavort.

Two sailors, end on end, hidden beneath a blanket, decide to go in for a spot of callisthenics. They’re just doing press-ups to keep warm, I try to convince myself; they have just been shipwrecked. The children around me know better.

An all-female Macbeth: I decide to be brave and get them in to act before Years 9 and l0. The pupils know the text. It will help prepare them for GCSEs. Within five minutes the dramatis personae are embracing each other so frantically we don’t like to intrude on their privacy, despite having paid for the performance. They follow up by smoking on stage in the school hall. The trick backfires, the pupils cough loudly and threaten to report them to the deputy head.

I’ve enjoyed teaching Shakespeare for many years. I know that each generation re-interprets the text in its own way. If Romeo and Juliet want to ride around in fast cars, packing heavy duty armoury, so be it. I don’t mind, if it opens up the play and makes us think. Cheap shock tactics, though, have a limited appeal. I find it sad that all my Year 7s will remember about Caliban was the size of his genitalia.

I’m angered that I can’t find out more about productions before I take the risk and bring my classes along. I don’t have time to see everything first. Reviews don’t always help and promotional literature just wants to get bums on seats.

I’m astonished that I don’t get any complaints. I agonise, sweat and squirm my way through these performances but nobody ever says anything. Perhaps I’m wrong to be concerned. I know I sound like a Victorian moralist having a bad day. I want the freedom to choose what to see. I’m not advocating censorship. I want our pupils to have open minds. I’m happy to tackle important issues arising from the performance. I’d iust like to avoid the embarrassment I sometimes feel.

I’ll carry on taking pupils to the theatre - it’s worthwhile in so many ways. But I’ll try to pick and choose even more carefully. Perhaps I’ll back a winner next time round.

It’s Measure for Measure at the Barbican in January. Now what can I expect to see in that?

Gavin Knight is head of English at St Edmund’s School, Dover, Kent