Totally enclosed by a circular seascape set, the children waved their model fish and sea-mammals (which, in true Blue Peter fashion, they'd prepared earlier), emitting sea-bird noises on cue and singing along to the story of Phil the Lost Whale.
"Putting children in a different environment is an essential ingredient to our work," says Malcolm Le Maistre, artistic director of Environmental Arts Theatre Company.
The Cockenzie kids were certainly taken by the show - though it was perhaps pitched a little above their heads - and the new environment. But they weren't totally happy with the idea of the illusion of theatre.
At question time after the show they wanted to know how everything worked. They showed that they knew what hand-puppets and rod-puppets were; and they knew how magnets worked though they hadn't been sure at first how Phil had managed to propel himself around the set.
"How did you make that?" asked one girl pointing at an imaginary "kelp forest" over her shoulder. A practical lot, these East Coast bairns.
Edinburgh-based Environmental Arts (patron David Bellamy) was set up in 1991 to create works of theatre about the environment using drama, music and visual art.
Music plays a large role, allowing sing-along participation; and that's not surprising given that Le Maistre is a former member of The Incredible String Band - "the first 'world music' band in history," as he puts it.
But story-telling is also central to their style as, in this production, they draw the pupils' attention to the examples of human pollution strewn around the set (and occasionally, it has to be said, strewn over the audience).
"A lot of it comes from boats," Le Maistre informs them. "But it's not the boats, it's human beings that throw it off."
"Yes," comes the reply. "Boats don't have hands." Quite right, too.
Thanks to financial suport from Scottish Power, Scottish Natural Heritage and East Lothian Council, the company is touring four different shows around East Lothian primaries until early next year.
Visiting every primary in the area they reckon that some 8,000 pupils will see their shows which, along with Phil the Lost Whale, include The Road (all you ever wanted to know about roads), The Swallows (an interactive performance telling of the history of swallow migration) and Diary of a Crisp Packet (tackling pollution in a suitably hands-on way).
Previous productions have included The Factor (looking at industry and the environment), The Pine and the Eagle (the story of Scotland's beautiful and tragic natural heritage) and No Smoke without Fire (an anti-smoking show used in workshops).
Further information from Environmental Arts Theatre Company, 6 New Street, Edinburgh EH8 8DW, tel: 0131 558 9889 Raymond Ross