You can always spot them - the new kids, first day in school. Here they come, a nervous look on their faces as they try to find the way in.
Some smart and scrubbed, ties carefully tied, top button done up. Some in jeans and trainers, like they don't care really. And in minutes they're being roughed up by the old hands who know all the ropes - and they can't even fight back.
Yes, it's tough being a father on Bring A Dad to School Day.
Welcome to Fair Oak infant school's bid to close the gender gap, get fathers more involved in school life and provide a positive example to boys who even in this middle-class Hampshire village are outstripped by the girls.
Headteacher Hazel Shaw points outs that with only one male teacher and a caretaker on site, male role models are in short supply.
"You have Bring your Daughter to Work Day so why not try Bring a Dad to School?" she says. Note that's Bring a Dad - stepdads, granddads, best mates' dads and other men from the non-nuclear 1990s are all welcome.
"Dads come in occasionally to read or go on trips, but they don't really get into the classroom. We have a lot of mums who help on a regular basis but currently no dads," Ms Shaw says.
"We want them to see what their children do in school so they can talk about it more, help them with their homework and generally be more involved. And we want the boys to see them in school, doing school activities, so they're more of a role model and the children don't just associate school with women."
The timetable is unchanged - no special football lessons or other typical dad activities. Dads muck in on this term's topics - fairy tales in reception, pirates and desert islands in Year 1 and all about the body in Year 2.
And the school is heaving with dads, each surrounded by a cluster of real and adopted offspring.
Shipwrecked dads, puppet-making dads, sewing dads, football-dribbling dads - dads everywhere. And not just the odd New Man dad, caring and sharing with his kids, or parent-governor dad doing his bit. No, there are 150 dads, squeezed into chairs, sprawled across carpets, juggling in the gym, shivering on the playground.
It's an eye-opener for all concerned. Simon Waller is having trouble with his spelling - but maybe he's just overwhelmed by his first day in school. Luckily his son Thomas is on hand to lead him through the minefield of Year 1.
"It's changed a lot since my day," he says. "Maybe it's just how I remember it, but it seems more relaxed. They don't seem worried about going up and asking questions - we did what we were told and kept quiet. They've got more opportunities. They've got computers - we had sand pits."
Eric Griffiths, relying on his grand-daughter in Year 2 to help him work out his height in metres, agrees. "We had none of this," he says, as Jennifer's classmates do a host of different activities in small groups. "It was all sitting in desks. This is better, so long as the teachers maintain some sort of control, which they seem to."
In reception, Chris Allen is under strict instructions from ruby-cheeked Ruby not to show her up. But he's still been naughty - and, worse, "Daddy didn't know how to sew," she yells, gleefully.
"Yeah, I've been shown up by all the girls and some of the boys as well," he admits. "Still, I hope it gives them the confidence to come to us with their work when we get home."
Nearby, four-year-olds are clambering all over Gary Lovell as he tries to build a tower from wooden blocks. His enthusiasm has got the better of him. "It's meant to be a giant's castle but it's turned into a bit of a conurbation," he says. Still, he is in the building trade. "It's difficult sometimes, especially when you're at work all the time," he admits. "You don't pick up the things they've been doing. They come home and you don't know what they've done because they won't tell you."
Most say the school should make it a regular event. Brilliant, Ms Shaw says - but they don't need to stand on ceremony. They're welcome any time.
"It's funny," she adds. "The dads have no concept of tidying up after themselves. Whatever they've been doing, they just get up and walk away. We thought that was very interesting."
In the gym, six dads and 30 children are lying motionless, breathing slowly, warming down at the end of the lesson. It's the quietest they've been all day.