It’s 10am at St Mary’s College in Derry and parents are gathered in the library. Some are dressed in their Sunday best, others in jeans; all are quiet and well behaved in the way of new pupils, listening in silence to the head spelling out the rules for the day, while behind them their daughters operate tea urns and give out pastries. Headteacher Dame Geraldine Keegan slips into a parody of herself, telling the adults with mock severity that they must pay attention, do as they are told and not talk to their neighbour. “You’ll find school a wee bit changed since your day,” she says. “Put up your hands if you’ll be using the canteen at lunchtime.” Most seem content to slip down the years into the tedium and comfort of being addressed by the head on a rainy Monday morning.

This all-girls Catholic secondary school in Northern Ireland has for the past 11 years run a “take your parent to school” day for the youngest pupils, in a neat reversal of the national “take your daughter to work” day (March 18 this year). It is an effective way, says Dame Geraldine, to involve parents in their children’s education and break down fears about entering school and talking to teachers. “It’s crucial that we work with parents. We need to raise levels of achievement in the school but that has to be an aspiration for the whole community if we’re to move out of a culture of disadvantage.”

More than two-thirds of the 150 Year 8 (equivalent to Year 7 in England) girls have brought their mothers. A sprinkling of fathers and one grandmother have also shown up. One girl dissolves into tears on hearing from a neighbour that her mother has overslept, but most collect their parents from the library - appearing delighted to see them - and take them off to their normal classes for the two lessons after break.

In a technology lab, a dozen women dutifully witness the operation of a sanding belt and listen as the teacher informs them that “the glue gun is the most dangerous piece of equipment”. When the practical work begins, one dons her daughter’s navy overall and wields a file on a small block of wood held in a vice. The atmosphere slowly warms up as parents contribute to the sawdust on the floor and talk to each other. “I used to go to St Mary’s, so it’s strange to be here,” is a typical opening line.

A language lesson follows, with extra chairs drafted in for a large-scale game of bingo using the numbers one to 20 and conducted entirely in Spanish. The room hums with daughters drilling their mothers in the numbers. Later, in the canteen, the girls pile their plates with curry, chips and garlic bread while the mums opt for salads and get the chance to rediscover boiled swede. After lunch they walk the puddled paths with their daughters, acquaint themselves with the sound of the St Mary’s chapel bell and experience again the sulphurous stink of science labs. Some seem to be looking around for the bike sheds.

Theresa McCullagh, 48, accompanying her 11-year-old daughter, Sarah, is a former pupil. “I loved it,” she says. “I loved every day at St Mary’s and all my teachers. I don’t see much of a change. It’s the same hustle and bustle, although it was stricter back then and I can see that the girls are more at ease.” Mrs McCullagh has brought in her own packed lunch, but this is at the insistence of her daughter rather than a reaction to bad memories of school dinners. “It’s OK, bringing your mother into school,” says Sarah.

“But it could be embarrassing, if you got a good comment from a teacher, or a bad one.”

By the time coffee is served in the library, the new girls are relaxed, chatting to each other and texting madly on their mobiles while their perfectly behaved daughters share their chairs and look happy.

Vivienne McBride, 33, left St Mary’s in 1989 and now has an 11-year-old daughter - Molly - at the school. “The decor’s the same and some of the teachers are still the same,” she says. “In fact, lots of them are. But the girls are allowed to talk in the corridors now; we weren’t, and we had to walk in silence in single file.”

Most of the teachers seem unfazed by the influx of new pupils, although one says she finds the day nerve-racking. “I hardly slept last night,” she says. Two more lessons follow in the afternoon, with parents dispersing for PE, religious education and science classes. One of the few dads - 48-year-old Kieron McGrory - takes time out from pounding red cabbage in a pestle and mortar in a “red cabbage indicator” experiment to comment on the changed educational climate since his day as a pupil of the Jesuits. “It’s nice to watch teachers in action with the girls. It’s not them and us, it’s we as a group.”

Dame Geraldine makes light of the practicalities of bringing large numbers of adults into the school. Costs are restricted to the lunches, coffee and refreshments provided for parents - less than pound;300, she says. Extra chairs from the hall are the only physical preparation made. “It seems so simple,” she says. “But you have to have an open climate and feel comfortable with the community coming into school.” She says the day is her favourite in the school calendar, and attributes part of its impressive results to getting parents involved. During the day, staff take the opportunity to invite parents to help out in school, and recruit them to parenting classes and lifelong learning.

At the end of lesson four, just before lunchtime, parents gather again in the library for an evaluation, some carrying the scones they’ve made in food tech. When Dame Geraldine canvasses comments on the day, only two emerge - that the parents’ day should begin earlier, at the same time the children start, and that it should happen once a month.

www.stmarys.derry.ni.sch.uk