There are schools where fathers can be seen. They drop off and pick up their children. They come along and help with the spring gardening project. A handful even listen to children reading for an hour a week. In other schools they are all but invisible.
The social profiles of these schools cover the spectrum, but the chances are that the staff in all of them face the same tricky problem of divorce and disappearing fathers. In leafy suburbs and rundown estates alike, fathers' races and cards for Father's Day are endangered primary school practices.
About 22 per cent of children are being brought up by a lone parent, according to the National Council for One Parent Families. A third will spend part of their lives in a one-parent family. And research suggests - though the council says the figure should be treated with caution - that half of separated fathers have lost contact with their children after two years.
Primary teachers must be sensitive to the children of divorced parents while not writing fathers out of the curriculum. It's even harder in the many schools which are bereft of male staff.
At Mary Trevelyan Primary School in Newcastle, which has an all-female teaching staff, more than 70 per cent of the 140 pupils are from single-parent families. Most are cared for by their mothers and more than 80 per cent qualify for free school meals. Yet the school - which is in Cruddas Park, an area of high unemployment and social problems - has an attendance rate of more than 90 per cent and above-average national test results. In the 13 years Mavis Grant has been head, there have been only two exclusions.
"We have to see things from the perspective of children who don't have an adult male in the family at all," she says. "The absence of the father is a big part of staff development.
"We have a tremendous record for managing children's behaviour and supporting children through problems. Often the school is the only stable and secure thing in their lives."
But she says the school's small size means it has lost promoted posts, which makes it harder to attract male teachers. "We try to get men into the school - Newcastle United and Newcastle basketball team members have come in to talk to the children.
"Not talking about it is the worst thing you can do. The children here know that I will stop whatever I'm doing if they need to talk. We had one 10-year-old whose father was sent to jail for a long time. He was either weepy and withdrawn or aggressive. I bought him a diary so he could write in the days when he was going to see his dad. It was a coping strategy.
"Times like Christmas and Dad's birthday are actually much harder than Father's Day. Perhaps we'll say: 'Let's draw Daddy a picture or write him a letter'."
Mavis Grant says the "broken promise" is the hardest thing for children of separated parents - "you can see from their faces on a Monday morning that Daddy didn't come when he said he would. That's very hard for them to handle. You can't ignore it. You have to talk about how everyone feels upset and disappointed from time to time. You find out what else the child did that weekend and you can ask if there's some nice thing she'd like to do in school today to compensate a little."
The school's homework club - with books, writing materials and other resources - helps. But sometimes the children simply want a cuddle which, Mrs Grant says, "sadly is an issue, even with an all-female staff. You can't push that child away, though you can perhaps try to hold hands instead. With the older children, an arm around the shoulder can make all the difference. Usually a child wants some one-to-one contact, someone to talk to. It's often hard for the mothers to talk because they're in pain themselves."
She says many children blame themselves for marriage break-ups - "you have children saying to you something like: 'I was always in trouble for not going to bed. I think that's why dad left'. You have to explain that it's not their fault."
Keith Hibbert, the principal educational psychologist for Newcastle who has worked with Mrs Grant on the staff seminars, says that if the children have been traumatised by violence, they will express it, often in role play and in doll play. Teachers can gain an insight and provide stability and continuity at a time when everything else is falling apart, he says. "Some schools can't do that and reject children because of difficult behaviour. It's about seeing beyond that behaviour."
Jim Parton, chairman of Families Need Fathers, a charity which campaigns to keep children in touch with separated parents, says the general absence of men in primary schools means separated fathers can find it a battle to be taken seriously as a parent. "I would like to see my son's report and I would like to be invited to the school for parents' evenings, but the system isn't geared up to include parents living at different addresses.
"Local education authorities should have a policy on it. Too often it's left up to the mother to tell the father of school matters. And that very often doesn't happen. My advice to fathers is to keep badgering away at the school. "
But things aren't always as simple as that, even where there's a willingness to add to the school paperwork. Mavis Grant says: "If we know where the fathers are we will send copies of school reports. But sometimes there's an injunction against the father, which we must obey. We leave parents' evenings up to the carer because of possible conflict. But I'm always happy to make separate arrangements to see the other parent."