It’s that time of year again. Stars shine bright in the night sky, snowdrops push up through the hard ground, starter motors grind to a noisy halt on frosty mornings. And pointy-headed aliens in bright orange spacesuits descend on our classrooms. Yes, the schools programme of the Edinburgh International Science Festival is under way.

Right now, at a secluded location in the city, grown men and women are trying on honeybee costumes, breaking out spaceship repair-kits and rehearsing lines carefully crafted to educate and enthral. New recruits, so confident and enthusiastic a few weeks ago, are starting to wish they had chosen less stressful jobs - test-pilot perhaps, or deep-sea diver - anything that does not involve wearing a day-glo suit while trying to convey the marvels and mysteries of science to children.

“When you arrive,” says Ensign Thuff from the planet Bong, also known as science communicator Louise Gee, “you enter this world of mad objects and weird props. Then you get a script and it’s quite nerve-racking - you lie awake wondering how you’re going to do it all. But once you get in front of the kids it all slots into place.”

This is the eighth year of the schools programme, which, from January 25 until late March, adds an extra dimension to Edinburgh’s International Science Festival in April, taking it out to schools beyond the city boundaries. Festival director Dr Simon Gage says: “Family visits are a priority at the main festival, which is always scheduled for the Lothian holidays. But that means it’s a bad time for school visits. So the schools programme was set up with the aim of providing stimulating activities for pupils and staff.

“The science festival only has a small permanent team, so each year we recruit 15 to 20 people and train them to do our shows. The tricky bit is deciding whether to recruit scientists and train them to act, or actors and teach them the science. This year we’ve got around half and half. But irrespective of their backgrounds, we’re putting a lot of effort into their training. At the moment they are all downstairs being put through their paces by a professional drama instructor.

“There are few organisations involved in this sort of thing, so the pool of experienced performers is fairly small. In Australia, they have a national science centre where they train science communicators, and we usually employ a few from there. Good science performers are remarkably hard to find though.”

But there is more to an effective schools programme than recruitment and training. Producing 20 different shows for children, and sending them out to 200 schools with a total audience of around 26,000 takes an extraordinary amount of backstage creativity.

Judith Procter, schools and family events manager, says: “Of the 20 shows going out this year, half were developed in-house and half brought in from outside.

“In response to feedback from teachers, we’ve tried to be clear about how each show ties in with the curriculum. The five-to-14 outcomes we concentrate on are understanding living things and the processes of life, understanding energy and forces, and understanding earth and space. There are also two shows on understanding people in the past.

“All schools should have received a copy of our booklet, which gives a brief description of each show and its target age group. And when they book a show we can provide more advice. We also send out teachers’ notes explaining in more detail what the show is about, how its science relates to the curriculum and what the school must provide - usually just space for the activity.

“Most of our shows are aimed at primary and early secondary, although there are some for older children such as the Brunel Space School, a five-day astronomy and space physics course for S4 to S6.”

Shows evolve in response to feedback from teachers and pupils, and several new ones are created each year. Responsibility for this rests with science communicator Jennifer Simpson.

“I come up with ideas, write the scripts and help train the communicators. But it’s not a solo effort,” she says. “I talk to science advisers about which areas are causing difficulty and I talk to teachers about what they want. Then I try to bring it all together.

“Audiences are becoming more sophisticated and demanding. The children are getting harder to impress, especially those in secondary school. So coming up with fresh ideas and putting them into practice can be exhausting, but it is also exciting.”

As well as feedback from participating schools, the Science Festival last year obtained one teacher’s perspective on the entire programme, by engaging chemistry principal teacher Pat Duchart to assess all the shows.

“Overall I was very impressed,” she says. “It’s much better to bring resources like these into a school than take the kids out, with all the implications for permission, cover, transport and safety.

“I particularly remember the show Little Giants. It was excellent. The performers did the waggle dance, showed how honey is made and went through the life-cycle of the bee. Their bee costume came apart to show the segments of an insect’s body.

“For the younger kids there was a puppet show about animals in the woods, which was also very good. And for the older ones there’s Starlab, which gives the children the opportunity to study the night sky. This year one of the new shows, about the Antarctic explorer Douglas Mawson, is a tremendous story of survival that I’m keen to see myself.”

“We use them most years,” says Cathy Harrison a teacher at Bonaly Primary School, Edinburgh. “Last year we got Madlab, an electronics workshop, for our Primary 4 classes, and the children could choose to make a lie-detector or a vampire with flashing eyes. They worked on circuit boards and learned how to solder, which built on project work we were doing. We could never have taught the kids how to solder, but the festival people brought all the equipment. The children had a fantastic time.”

“We had Starlab set up in our science hall,” says physics teacher Fraser Donnelly of Dunfermline High School, “and the kids came in throughout the day, studied the stars and learned all about them. It was only here for a day, which was a pity because we could easily have used it for longer. Everybody enjoyed the show, including the staff - we couldn’t get the teachers out of the planetarium.”

New shows in the schools programme this year include Ingenious Genes (unravel the mysteries of DNA), Explore the Sea (get to grips with living starfish, anemones and crabs), Paint Set (grind your own pigment using minerals from the Earth, and paint a papyrus scroll), and the Big Science Roadshow, an imaginative introduction to astronomy, space travel, alien atmospheres and the origin of the universe.

To book a show schools should tel: 0131 473 2070, Monday to Friday, 8.45am to 4pm. Schools outside a 40-mile radius of Edinburgh will be asked to make a nominal contribution towards travelling costs