Douglas Blane introduces the first of a weekly series on the Edinburgh International Science Festival
As the two men grasping the sheet of black plastic stare into the muzzle of the potato gun, they have the same thought: perhaps Dr Bunhead has chosen them from the audience not for the firmness of their grip but because they are expendable.
His target is supposed to be the tennis racket in front of them, but maybe his idea of a good energy and forces demonstration is not just to "blow up perfectly innocent vegetables", but to bounce one of them off the forehead of a perfectly innocent parent.
Bunhead after all, gaily bedecked in orange, purple and green patchwork labcoat, does not look entirely normal. He may be a mad scientist. He is certainly capable of carrying on both ends of a conversation with a banana as he lowers it into a vat of bubbling liquid nitrogen, then using it to hammer a nail into a piece of wood. He is capable of giving an animated impression of an ardent young firefly, its wiggling behind aglow with the green light of love.
But is he capable of blasting a grown-up with a King Edward for the entertainment and education of the kids? And if "potato gun" conveys the idea of one of those children's toys that fires little potato pellets, dispel it. This thing is a metre long, needs two hands to lift it and fires entire potatoes. Big ones. Exactly how hard we are about to find out.
Bunhead is building the tension, fiddling with the lighter that will ignite the explosive.
Allan's Primary Schol in Stirling is an historic old building on the road to the castle, but what happens inside is entirely modern. Science and technology feature prominently, and today is the first session of the science supported-study group which has been set up by depute head Lindsey Howland: "Next week we'll be helping the children develop their own ideas for activities, but for this first one I thought it would be nice to get Dr Bunhead to give them a show."
It's a good choice. Bunhead may look and act like a loony, but behind the clowning is the brain of first-class science teacher Tom Pringle, whose shows are carefully choreographed sequences of tension and release, with moments of madness and mayhem interspersed with little sessions that tease out the children's scientific ideas and misconceptions, build their confidence, and guide them in the right direction.
At the climax of the show Bunhead finally has everything to his satisfaction. He slowly raises the huge gun, takes aim and pulls the trigger. There is a tremendous BANG! and the potato flies through the air, hits its target, passes clean through and, to the relief of the nervous assistants, is caught in the plastic sheeting. Bunhead dances round and holds up what's left of it. "Look," he cries."Instant chips!" Dr Bunhead's Exploding Energy Show is part of the Edinburgh International Science Festival schools programme, tel: 0131 473 2070.Dr Bunhead tours schools throughout the year. For more information visit the website at www.bunhead.com, or email firstname.lastname@example.org