The overhead lights are switched off, an order is given and the classroom becomes a cavern, illuminated by the candle-like glow of dozens of tiny electric bulbs.
Kathleen Bull beams at her group of Primary 6 scientists and announces: "OK, your lights work. Now try your buzzers."
The overheads come on again and, seconds later, the room vibrates with the waspish drone of electrical buzzers, sparked into life by circuits deftly built by the 15 members of the after-school science club at Middlefield Primary in Aberdeen.
"Silence!" booms the visiting club co-ordinator. "When I give the word, we're going to have a buzzing concert."
The hush is momentary, broken by an over-enthusiastic boy who just can't leave his device alone.
Mrs Bull's frown is formidable but she doesn't sustain it for long. She gives the word, prompting another ear-tickling session that delights the children, who revel in their power over a couple of batteries, some wires and a buzzer.
The noise is a reflection of the enthusiasm generated by the energetic scientist's weekly visits to the school. These began two years ago with the advent of an after-school outreach programme for P5-P7 pupils. Run by Satrosphere, the city's livewire interactive science centre, the programme brings pupils at schools in designated social inclusion zones the opportunity to experiment with a range of fun activities designed to demonstrate the everyday wonders of science.
Last term, among other topics relating to the 5-14 curriculum, the four schools participating in the programme were tackling recycling plastics, paper making, astronomy, "stretchy" science - demonstrated by a bungee jumping teddy bear - and electricity.
Today's circuit-building session is noisy but Mrs Bull - who likes to be called Kathleen by the children - is in control and throughout the hour-long session she masterfully maintains the delicate balance between excitement and disruption.
"I don't have a teaching background - I was a university research technician before joining Satrosphere - but I do have two children of my own," she explains. "Science, for me, is very exciting and I'd far rather the children throw themselves into the activities and constantly ask questions than have them sit quietly and have to be chivvied along. They learn and remember better if they are active participants and have a good time into the bargain."
This afternoon, the group is building on the previous experience of putting together a basic circuit and is solving the problem of how to create a more sophisticated set-up that gives maximum power to two light bulbs. They are also investigating electrical conductivity by running a current through different objects and recording the results.
Each practical stage is reinforced by a brief discussion of what they have learned, as well as positive messages about their achievements, ending with: "As scientific investigators, you've set up an experiment, recorded the results and reached a scientific conclusion. Well done!"
Success is also celebrated at the end of term, when children from the participating schools, having completed 10 activities, are presented with British Association Youth Section badges and certificates at a school assembly.
"It's a very rewarding moment to see the delight on their faces as the children come forward to collect their awards," says Mrs Bull.
Middlefield Primary headteacher Catherine Taylor has no doubt as to the benefits the club brings to her school.
"Kathleen is an expert and she supports each session with materials the children may not have access to in class. They are all very enthusiastic about the science club.
"Attending the club also provides support and development opportunities to members of staff who may lack confidence in some areas of science."
Satrosphere's outreach work at Middlefield, Walker Road, Springhill and Muirfield primary schools in Aberdeen will soon be extended to other schools in the area thanks to a grant of pound;8,000 from the Lloyds TSB Foundation for Scotland. The target is 300 science club sessions a year, potentially reaching 6,000 youngsters.
Meanwhile, other children in the area can sign up for a newly reformed after-school club at Satrosphere itself. The Tramshed Kids (named after the centre's new purpose-built location near Aberdeen Beach) continues the tradition of the popular BP-sponsored Basement Bunch, which ran for several years at the old premises.
Further opportunities for schools to benefit from Satrosphere's fun, curriculum complementary activities are being supported by Aberdeen City Council. It has set aside pound;50,000 to enable every primary age pupil in the city - 16,000 children in all - to spend an Active Science Day at the hands-on centre before March. Satrosphere chief executive Per Arno has described this as "an important step towards inspiring a lifelong interest in science throughout our community".
At Middlefield Primary, the seven girls and eight boys who have come to the club, despite the fierce weather, are clearly inspired by their own in-house experience of Satrosphere. "It's fun," they say. "Science is really interesting." "I'm here every Thursday." "We do fantastic experiments." "It's worth far more than the pound;1.50 we pay each week."
"I'd recommend this club to all children everywhere."
That would seem to prove - albeit in a non-scientific manner - that the project is a success.