Here’s a great experiment for you to do. You need a marshmallow and the microscale vacuum apparatus. If you can’t lay your hands on the latter, put the marshmallow into a clear (empty) wine bottle and attach one of those wee hand pumps designed to remove air to keep the wine fresh. As you drop the pressure, you’ll see the marshmallow grow larger as the air pockets inside it expand. You can see my niece inflate a sealed balloon in a similar manner on the SSERCphysics Facebook page.

I love to do the marshmallow experiment in front of young children, adding a bit of theatre. “This is my giant sweetie-making machine!” Giggles and hands over mouths as the marshmallow gets bigger (from them, not me). “I can’t wait to eat my giant sweetie!” Pause. “Here we go... ah” As you depressurise the bottle to get the marshmallow out, the giant sweetie of course collapses back to its normal size.

I’ve heard of two cases now in which this has been too much for an onlooker who has burst into tears, once when a marshmallow man was used and once when the demo was done by one of the sweetest, gentlest physics teachers I know. Looks like we’ll have to add possible emotional damage to the risk assessment.

By the time you read this we will have run (weather permitting) a demonstrations course. A fair number of the things we show can be hyped up to look like magic tricks. You could put them all together and have a science show. But is this a good idea?

There are some highly engaging, funny science presenters out there, though I wish they didn’t feel the need to assume academic titles and surnames that suggest explosions. Sometimes, on TV or at a school near you, they do hit-and-run science, with demo after demo and no theory. I’ll admit that I’ve spent an hour with a class and a Van de Graaff generator that taught them only that VdGs were hilarious, but I had the next period to cover the science of what was going on. Still, Professor Percussion might well give the impression that science is something wonderful. My problem is that few of the children will ever want to be Professor Percussion, or believe that they can be a “scientist” like him (invariably “him”).

All of us in science education have to be careful not to come over as some sort of Grand Wizard, keeper of the secret knowledge that lets us call fire from the heavens, make things appear and disappear, raise hair at the flick of a switch. It could be rule 2, after “don’t be boring”.

Gregor Steele can’t really talk, having been described as ‘looking like a total mad professor, nae offence’ by one student.