"Give me the daggers," hisses Lady Macbeth and, wresting the offending weapons from her husband's grip, she thwacks him over the head with them. It isn't in the script, but it does serve him right. He should have stopped stabbing her at the twelfth time of asking.
Stab 13 was particularly unlucky as it prompted Duncan and Banquo to get involved. And if they hadn't chased Macbeth across the blasted heath, the set would not have been demolished and the Second Witch would have had no cause to throw a cauldron of poisoned entrails at them.
That cauldron took a space hopper, buckets of papier mache, our entire stock of black paint and the best part of a fortnight to construct. And now is not the right time of the month to ask the props department to make another one.
It is that time of year when we conspire to generate several crises in the name of making a drama out of them. And although I know that at this stage rehearsals tend to be chaotic, for some reason we seem more disaster prone than usual. Are we cursed?
By tradition, our end-of-year production is a Shakespeare adaptation. This year, we are transforming Macbeth into an all-singing, all-dancing theatrical experience called The Day the Woods Came to Dunsinane. It is a murderous tale of ambition, witchcraft and landscape gardening.
But the omens seem to foreshadow a disaster. Our music teacher has declared that she will have nothing to do with Macbeth on religious grounds - it being steeped in witchcraft and the black arts - while Year 6's mood swings are veering from wild hysteria to sullen episodes of PTSD.
PTSD (Post Traumatic Sats Disorder) afflicts children who have undergone eight-and-a-half months of intense cramming - including an Easter boot camp and countless after-school "embedding learning" sessions. They wander the corridors like pale ghosts, mumbling random phrases such as "alliteration is when words begin with the same sounds" and "to find a fraction divide by the denominator and times your answer by the numerator".
And now, to compound matters, there is the cast of 2011. Clearly, the chance to perform in front of hundreds of adoring family members attracts a certain personality type. This year, it has brought forth the most melodramatic, egotistical, emotional, impetuous, impulsive, intolerant, domineering, disorderly and unruly bunch of "dramatically" gifted and talented children that ever reduced a director to a gibbering wreck.
With rehearsals running out, my resolve founders. I wring my hands and cry, "If we should fail?"
At this point, our choreography department (aka Tracy) pats me reassuringly on the head: "We fail, but screw your courage to the sticking place and we'll not fail."
Yeah, now where have I heard that before?
Steve Eddison is a key stage 2 teacher in Sheffield. The Day the Woods Came to Dunsinane is at the Montgomery Theatre, Sheffield, on 7 July.