Baby Jesus freaks: Amazing what you can do with four stuffed lambs and a jar of bath salts. But the modern nativity welcomes Christ with Jean-Michel Jarre and a smoke machine

'IT'S absolute mayhem,' says someone in the staff room, 'they've been high as kites all morning.' In the playground the leaf men, who've come to clear away the autumn debris, dart nervous looks up at the school building, and the person who arrived to mend the photocopier is seen sloping away towards the main gate. With a pained expression, the headmaster is pinning decorations to the noticeboard. And in the classrooms - knee-deep in tinsel and wet paint and excited children - there is the sound of teachers dangling from the end of their tether: 'OK, but quickly Aaron,' they shriek above the hullabaloo, or: 'Do you want this class to begin or not?'

It is a scene you can find in any part of the country. From Hampstead to Leicester, Bradford to Bath; December strikes

chaos into the heart of the primary school. And there is one thing to blame: the nativity play. The simple story of the 'first Christmas', of birth, love and, er . . . peace, is transmuted, via a Tiny Tears doll, a packet of gold stars and a blue candlewick bedspread, into a human endurance test. 'You'll have to excuse us,' says Mrs Tucker from St Thomas More in Leicester, who's has spent the morning up to her ears in shepherds' costumes. 'We're not at our best today.'

And would anyone wish things otherwise? For most schools, the nativity play is a vital ingredient of the year's activities. 'As adults we may know the story well,' Mrs Tucker says, 'but for children it's often the first time they've heard it - and we like to teach them from the word go.' 'Every year we do it,' says Sue McCoy from West Heath Junior in Birmingham, 'and every year they've forgotten what it's about.' 'We just think it's a tradition,' says Mrs Dean from Glade County Primary Infant School in Bognor. 'It's a joy and it's part of our heritage, isn't it?'

Not that the nativity is always delivered straight. Church schools may veer towards the conventional: Mrs Tucker says Christmas wouldn't be Christmas without the same four stuffed lambs and jar of bath salts - 'They've been around as long as I've been here, which is, oh, 16 years.' But schools that figure a wider cross-section of religions and cultures tend to deploy a little artistic licence. This year, at Glade County, they're showing the birth of Jesus through the eyes of a group of stars. At Tatworth School in Somerset they serve home-made punch and 'have a good old ham of it' (one of the wise men brings Camel Pie and a camel in the next door stable cries 'Oh no, not Uncle Lenny'). And at Grayshott School in Hampshire, the Gold Class (aged 10-11) performs 'The Three Wise Spacemen' which takes 'an intergalactic look at the age-old Nativity story' and centres on something called a Bedmobile.

Grayshott has a number of 'winter visitors' (travellers, who only attend the school from October to March), and this year the father of one of the winter children has lent some flashing lights and a smoke machine. So, what with the vagaries of time travel, a handful of dance interludes - to Jean-Michel Jarre's 'Oxygene' - and some business with an old car, there isn't an awful lot of time left over for the climactic nativity scene. This doesn't bother Mary (aka Rachel): 'It's boring. Everyone says he's my boyfriend and calls me Mary in class and I wouldn't want three strangers watching me have a baby anyway.' Or Joseph (aka John): he thinks Mary's fussy. 'Anyway if we did the whole thing,' says Michael, who plays a Stone Age father, 'it would take yonks and yonks and yonks and yonks.' 'And yonks,' adds Graham, one of Robin Hood's men.

Val Palmer, the class teacher, finds that at this age it's the details that grab them - the props, the lights, the knobs on the Bedmobile - and that the experience is useful primarily 'for the building of confidence; they learn to work together, to take responsibility for something'. Chris Brown, Grayshott's headmaster, believes it's important to 'teach them respect for the influence of religion, but to keep the imagination open rather than shutting the door'. Some of his pupils come from Christian families, others do not. 'And it's impossible to generalise about how much the children understand the story, or its relevance. The conceptual understanding of a five-year-old can be completely different from that of a six- or seven-year-old. Though you could say younger children tend to be very factual; they tidy up intangibles.'

Certainly, while nearly all the infants will tell you politely that Christmas is 'when Baby Jesus was born', their imaginations seem to be entangled with the practicalities of the narrative. Choosing the boy and girl to play Joseph and Mary is never very difficult. As Chris Brown says: 'It's whoever doesn't object to having to touch each other - once you've got over that hurdle there isn't an enormous selection.' But different factors can come into play. Alex, aged seven, who plays Joseph in an 'old-time musical' Christmas show at St Andrews in Oxford, notes how 'appropriate it was for me to be Joseph because Joseph was a carpenter and I like carpentry too and I've made a birdbox and I didn't have anything on my feet because they didn't wear anything on their feet indoors'. Megan, 11, from Grayshott describes Mary, through a mouthful of Monster Munch, as 'a blue person who has a bad taste in clothes'. And Siobhan, aged six, defines angels as 'flying people' and talks about being in 'an activity play'.

Teachers say that, these days, it's rare for non-Christian parents to remove their children from the nativity, although Jehovah's Witnesses usually do stand back ('It can be quite useful,' says one teacher, 'we get them to do some jobs around the school, you know - photocopying, general secretarial . . .') which, considering the secular nature of many nativity plays, is a shame. After all, the real religious celebration usually comes later. 'The day after the play, we hold our last assembly in the local church,' Chris Brown says. 'After the hustle and bustle, it's lovely and peaceful and quiet. The props and the costumes are packed up. Everyone else has gone and it's just us.'

Geoff Franklin's nativity photographs are at Metro Photographic, 45 Clerkenwell Road, London EC1, until 6 January.

(Photographs omitted)