Celebrity chef Jamie Oliver has shaken up the world of school catering with his crusade to improve what school children eat, but will it lead to better educational results as well as healthier pupils?
For 25 years Eileen Miller has watched pupils consume all manner of food, but recently she found it increasingly difficult to encourage them to eat up what they were served in the school canteen.
Chicken nuggets, instant mashed potato, chips - everything most children love to gobble up. And then they sit in the classroom getting grumpy and sleepy, unwilling or unable to learn from the exasperated teacher.
But since Our Lady of Grace primary school became one of the 30 schools in the London borough of Greenwich to change its catering, things have improved, Mrs Miller says.
"It's only been in the last couple of years that I've felt that this is horrible. There have been more convenience foods coming in - the cooks just have to slide them in and take them out when they are hot. It's desperately bad for the children."
Now a typical school dinner could be lamb casserole, always a salad -" not those big lettuce leaves, but chopped finely" - and new potatoes with butter.
"Now we see the food arrive here and we know that it's good quality and well prepared, so we're quite justified in saying to the children 'please have a go at eating it'."
And the results in the classrooms and playground have been noticed by all staff teaching the 200 children aged four to 11.
"Before the children were quite lively, they were quite a trial," she says diplomatically.
"Then suddenly they are getting on in the afternoon and incidents of fighting have gone down. They are no longer pumped up on E numbers."
But while the teachers appreciate the difference (and have even swapped packed lunches for school dinners), the children may be less aware.
"They don't really take [any changes] on board. They don't suddenly think 'gosh, I've got cleverer'. They just feel happier rather than uptight.
"We're giving them the best chance, because if they are cross or agitated they are not ready to absorb new ideas," she says.
Smiley faces can make for grumpy, irritable children
Figures from the Department for Education and Skills seem to back up the idea that healthy children lead to better educational results.
Its Healthy Schools programme, running since 1999, aims to promote a healthy lifestyle and includes the National Healthy School Standard which schools can sign up to.
Healthy eating is one of the eight themes of the standard, including sex and relationship education, citizenship and physical activity.
To see if there was any link between healthy schools and a rise in standards, the change in the total proportion of primary school children who achieved level 4 or higher in English, Maths and Science was assessed.
Of the 2,314 schools who were part of the Healthy Schools programme, there was an increase from 2003 to 2004 of 3.6 percentage points and from 2002 to 2004 of 3.8.
This was above the average improvement in the 1,200 schools who did not participate. Over one year there was an improvement of 2.18 points and over the two years it was 2.91.
Specialist dietician Paul Sacher, from Great Ormond Street Children's Hospital, emphasises that evidence shows children who eat healthily and regularly can expect better concentration and more steady energy levels.
If a child misses breakfast - the most important meal of the day, according to Mr Sacher - and then reaches for the crisps at break time "they go from having nothing to being bursting with energy".
"It's an unnatural high, and they become very difficult to manage."
Processed and refined foods can lead to ups and down in blood sugar, which can lead to children being overcharged with energy quickly but then sleepy in the afternoon.
"To concentrate you need a steady supply of blood sugar. Otherwise you get a rapid rise and drop - hyperactivity and lethargy," Mr Sacher said.
Jamie Oliver is pushing for healthier eating in schools
And what the child is drinking is just as much the culprit as their food. Sugar and caffeine, common and plentiful in many drinks, can make children hyperactive.
However, the much-reviled E numbers of preservatives and additives can't be blamed, Mr Sacher said.
"There is no firm scientific evidence that E numbers can cause bad behaviours, but they might do in some children."
His prescription to get children away from "these nuggets and dinosaur feet they're fed these days" is to encourage them how to learn to prepare food, with their parents, and even to grow their own food.
"If you fire up their imagination, then they are more likely to eat something which is interesting and fun."