It's a maths lesson and after a group activity it's time to go through the workbooks. Like many other primary teachers, Julie Genovesa helps the children individually with the exercises. Unlike many others, the pupils have to come to her.
For Julie this is one of the most frustrating parts of teaching. "I don't like not being able to turn the pages of their books or show them how to lay a sum out," she says. "I would like to be able to wander up to them instead of them having to come up to me."
Julie has motor neurone disease (MND), a condition that destroys the cells that control her muscles. She has no movement below the neck, uses a wheelchair and breathes through a ventilator, but she is determined to carry on teaching as long as she can. "It didn't occur to me not to work. I'm not a martyr; I just adore my job."
Julie was diagnosed with MND four years ago after a colleague pointed out that she was always out of breath when she reached her first-floor classroom, at Buttsbury Juniors in Billericay, Essex.
After an exhaustive series of tests, she was told she had a progressive and incurable form of the disease. She was given 18 months to two years to live. "It was a horrible shock. Everything was good in our lives. I had a six-year-old son, a job that I loved, and then bang, this happens," says Julie, 51.
Her GP wanted to sign her off permanently but Julie was determined to carry on. After speaking to Vaughan Collier, the headteacher, it was agreed that she would come back to work three days a week, Monday to Wednesday. She would have a teaching assistant for afternoons as well as mornings, and move to a downstairs classroom.
At that stage Julie was using a walking stick. The school already had a disabled toilet and a ramp installed for a former pupil. "There were barriers, but I worked on the supposition that if she was fit to teach medically, there was no reason for her not to continue," Vaughan says.
Julie's return to work - three months after diagnosis - didn't start well, though. She tripped and split her head open on her first day back. On another occasion, she fell down in the toilet and a colleague had to kick open the door.
Within six months she realised that she could not postpone it any longer and opted to use a wheelchair. "It wasn't fair on the children to see Miss fall over," she says.
A voice-activated computer provided by the school means Julie can surf the internet looking for resources and ideas, and her desk is raised so the wheelchair can fit underneath it. Fortunately, the colleague who shares her Year 4 class is very tall.
Wendy Wright, Julie's teaching assistant (TA), operates the whiteboard, wheels Julie around the classroom and writes down Julie's comments on homework. "Wendy is not a normal TA. She is my hands and my legs," Julie says.
"We often think on the same wavelength because we've been working together so long," Wendy adds.
Julie went on to the ventilator full-time two years ago. She lets the children handle it so it doesn't scare them. "Children are adaptable and accepting. The main thing they ask is how I go to the toilet. I just say: 'Like everybody else'," she says.
Four years after her diagnosis her condition has reached something of a plateau. Assessments of her life expectancy have been somewhat revised. "We all thought this was going to be for a year at the most. Nobody thought I was still going to be here now," she says. "Coming into work gives me a reason for getting up. I'm convinced that I wouldn't be here now if I had given up."
While Julie's struggle was to get back into the classroom, for Sab Sahota-Lyons the challenge was to get there in the first place. At the age of 8, Sab contracted Still's Disease, a form of arthritis that can inflame the eye as well as joints. By 18, she needed a scribe to do her A-levels. By 22, she was almost completely blind.
She wasn't going to give up on her dream of becoming a teacher, though. "I never stopped to think that it might be difficult. That was what I wanted to do and the fact that people said I wouldn't be able to made me more determined," she says.
She got three interviews from 18 applications but acknowledges that she was lucky enough to be championed by the then head of English at the Priory School in Lewes, East Sussex. Her six-month placement at Priory during her PGCE at Chichester University proved she could manage in the classroom. The only setback was an interview at another school, where the head asked if she was worried about walking into walls. "I thought: 'What a stupid question,' but I just said: 'No, of course not'," says Sab, who uses a cane but has resisted getting a guide dog for fear of becoming too reliant on it.
Sab, 36 and a mother of three, is in her 12th year at Priory, where she is now head of English and a head of house, after a stint as head of year.
She doesn't expect the children to be nicer to her than to other teachers, but those who think they can get away with more in her classroom are often in for a rude awakening. "My hearing is very good so I know what is going on," she says. "I can make out I'm not concentrating and sometimes the kids wonder whether I can actually see."
She can tell if a pupil is still wearing a coat; she can hear them eating; she recognises voices quickly; and she knows whether someone is standing up or sitting down. It takes her about a week to get to know all the children's names and voices, so she knows who is playing up and who is working quietly. She's always worked alone in the class, giving her self-reliance.
Perhaps because she can't write things down, her memory is particularly good, which helps her to be consistent. "I never, ever forget, and discipline is not an issue."
Technology can be, though. Her laptop has speech software in it so she can surf the internet, although it is time-consuming as she has to click on every link to find out what it is. She relies on pupils to help operate classroom equipment, including the whiteboard. "I have to trust the kids to do it and you can only do it with classes you are comfortable with," she says.
As head of department, she has a teaching assistant to help with administration, making sure books and worksheets are in the right place and doing any photocopying she needs. Sab gets a local authority grant to pay markers, at pound;6 an hour. While the markers, often student teachers, go through the spelling, punctuation and grammar, more detailed comments mean they have to read the work aloud to Sab over the phone. One set of GCSE essays can take about 10 hours, usually completed in one- or two-hour slots. "Finding the time is one of the hardest challenges," Sab says. She also has to find the markers herself, which can prove difficult for a task she admits is boring. With the extra time she has to spend on preparation and marking, it helps that husband Deane stays at home to look after their daughters.
Children compete for the honour to be her "eyes" in each lesson, picking pupils to answer questions, with strict instructions not to keep choosing the same people and to alternate the sexes.
Reaction from parents has been positive, apart from the one in Sab's first term who complained that a blind teacher would be ineffective. "It upset me because it was so personal and there was nothing I could do about it," she says. The pupil stayed in her class for the next four years, though, and his mother didn't complain again. "I got a lot of support from the school and just went back to work. It would take a lot to upset me now."
Her next goal is to be an assistant head, although that may have to wait until her daughters are older. She acknowledges that there will be obstacles in moving to another school: she believes it was her disability that stopped her getting more interviews when she was starting out, but it isn't going to deter her.
"It is something I will just have to face - there's no point pretending it isn't there," she says
What is expected of schools?
Voice-activated software, ramps and disabled toilets may not come cheap, but failing to adapt your school for disabled teachers can come at an even higher cost.
Gaynor Meikle taught domestic science at The Gedling School in Nottingham for 11 years, but when she started to lose her sight, the school refused to increase the font size of her teaching materials.
Forced to leave her job, Gaynor took the case to the Court of Appeal, which ruled she had been constructively dismissed and ordered Nottingham City Council to pay pound;196,000 compensation.
The case, resolved in 2004, was a landmark for the Disability Rights Commission, now superseded by the Equality and Human Rights Commission. A commission spokeswoman says that under the 1995 Disability Discrimination Act an employer must make "reasonable" adjustments.
"The range of reasonable adjustments could go from markings on the floor for people with visual impairments, to having a support worker or making alterations to the premises," she says.
Access to Work, a government programme, offers grants towards the additional costs of paying a disabled employee.
The commission has a helpline for people who feel they have been discriminated against: 08457 622 633.