The whole of southern Scotland once lay deep under water and those days could return sooner than anyone expected. Splash may well be the wettest workshop ever devised, and the smartly-dressed teachers at Holytown Primary School, North Lanarkshire, soon realise why Cat Somerville and Lori Moffat are presenting the show in jeans and wellie boots. Sou’westers and oilskins would be handy. Lifejackets would not be out of place.

The show invites children to “look at different boat shapes, race your boat, add a sail, create a storm and have lots of watery fun”, so a little water might be expected. But it is rippling in narrow metal tanks, sloshing in brightly coloured boxes, glugging in fat plastic bottles and splashing around in a big, blue paddling pool shaped like a seashell. And since this is the second show of the morning to an audience of infants, there are, besides all this deliberate water, several gallons of casual water with which one woman and a mop are fighting a grimly determined, but clearly losing battle.

The kids are having a ball and the teachers too have rolled up their sleeves and jumped right in. There is a great deal of teaching going on, both by the presenters, who are moving around helping little hands and guiding little brains, and by the teachers.

Learning is perhaps a different matter because the show’s designers ave occasionally let the variety that holds an infant’s attention stray too far towards complexity. Racing little boats with more than a dozen shapes, sizes and colours of sail is certainly appealing - but it is also confusing. And while four of the six investigations that make up the workshop are fun, interesting and scientifically unexceptionable, there is a problem with the other two.

The boat races demonstrate, in an entertaining and exciting way, the effects of forces and the difference the shape of a ship or the size of its sail can make to its speed. And the show’s designers have tried to make the tests fair by using identical little fans or weights to propel the ships. Unfortunately there are other variables - such as the response times of the children - which are both uncontrolled and, especially with water tanks just a few feet long, significant.

When primary teachers who freely admit they need help with science call in the experts, they are entitled to expect that their pupils will not, however inadvertently, acquire misguided notions - such as, that fat hulls or small sails make a ship go faster. This is especially important when the quality of the presentation ensures that the lesson will be remembered when others have long been forgotten.

Splash could benefit from a brief spell back on the slips before it is launched again. In school science if you are going to be memorable, you have to be right.

Edinburgh International Science Festival, tel 0131 555 6626