Want to know the secret of a calm school? Take lunch seriously. Since Southey Green junior school, on the outskirts of Sheffield, reviewed its attitude to lunchtime, staff have noticed a big improvement in children’s behaviour.

“Most come in very calmly after lunch and are ready to settle down in the afternoon,” says Year 3 teacher Carole Dent, who has been at the school for 23 years. “There’s less arguing and fewer problems than there were before.”

Lunchtime at Southey Green used to be a free-for-all, with queues stretching out of the dining room into the corridors. Most children brought in sandwiches so they could spend the break dashing around the playground. After lunch the bench outside the head’s office was crowded with miscreants.

Then headteacher Joe Dunn changed the way school dinners were served, transforming the meal from eat-and-run into an important part of the children’s day. He believes it has boosted their self-esteem, and made lunchtime a more sociable occasion, as well as dramatically increasing the number of children getting a proper daily meal. “It’s the only hot meal some of them get,” he says.

More than half of Southey Green’s pupils are entitled to free school meals. But when Mr Dunn took over as head four years ago, more than two in three pupils were bringing in sandwiches, with many missing out on their free meal entitlement.

The school had a “flight tray” system, where children queued for lunch. “They had to wait for long periods. Some were going out on the yard before they’d had lunch. And the noise was terrible: children were shouting across the dining room if their friends were there. It wasn’t a calm, orderly atmosphere.”

School dinners were definitely uncool. But the high number of sandwich eaters had serious implications for Southey Green, which was losing out on funding because take-up of free meals is an important element in Ofsted’s performance and assessment (Panda) reports.

The changes to the way lunchtime is organised have reversed the ratio: two out of three pupils now have school meals.

Under the new system, Year 5 and 6 pupils work as servers. At lunchtime they line up in pairs and Joe Dunn leads them to the dining room. While the rest of the school has a brief playtime outside, each pair of servers goes to their allocated table. They lay out knives and forks, beakers and water jugs, then sit upright, arms folded. The remaining 340 children come in and take their seats.

Tracksuited Mr Dunn blows a whistle to hush them and patrols the room, inspecting them like a benign sergeant major. “That’s a lovely table,” he says to one group who are sitting neatly with arms folded. They are today’s winners of the “star table” prize.

Finally, the Year 5s and 6s stand and serve lunch, serving themselves last, and the children tuck into pizza, saute potatoes and baked beans, followed by carrot cake and custard.

Mr Dunn was a regional lifetime achievement winner in the 2002 teaching awards; he used his prize money to help redecorate the dining halls, which now have blue walls and yellow doors. Every day he and his deputy, Linda Coulson, supervise lunchtime with the help of learning support assistants.

“The flight tray system we had gave no sense of community,” says Linda Coulson. “Spending time eating together and all the important skills that go with that, like socialising and table manners, weren’t there at all. It’s had a huge impact on behaviour: they sit down and relax. It’s raised the whole level of expectations at lunchtime; they much prefer it. It’s time for them to talk and have a conversation over dinner.

“And it’s given the servers some responsibility. They have a sense of authority which the other children respect.”

Carole Dent says: “They get the opportunity to run off steam at lunchtime, but they also have the socialising opportunity in the middle when they have sat at table. And they do come back calmer. I have noticed the difference when we’ve taken the children out on trips and they eat together.

“There’s been a big improvement in the way they eat and the way they socialise at the table. Their manners are better and they’re using their knives and forks properly. And they are more pleasant to each other.”