These developmental stages, so strongly programmed, have traditionally dictated learning programmes for severely disabled children. Pupils have been helped, often with great difficulty and over long periods of time, first to "respond" then to turn, roll, crawl and reach. Rarely, and only when the earlier hurdles have been crossed, they might have been taught to stand or walk.
But the MOVE (Mobility Opportunities Via Education) programme turns traditional thinking on its head. It starts by looking at the child with profound and multiple learning difficulties who sits - half lies - in a special chair, head to one side, being lovingly attended and given a range of stimulation, and says, in effect: "Let's get her on her feet."
Stanton Vale School in Derbyshire is the kind of school where you would expect to see lots of young people sitting and lying. But the first thing you notice is the number of pupils standing up. Stanton Vale has 65 pupils,23 of them on the MOVE programme.
It seems so obvious. Get a boy with severe cerebral palsy out of his wheelchair and into a frame that will support him upright. Adjust it so he can push his legs against the ground. Then see his legs strengthen. Watch him try to kick a football. Look him in the eye as a fellow inhabitant of the upright world. See his whole demeanour improve - to say nothing of his circulation and digestion.
Then watch as the supports on his frame are adjusted over time until - and it does happen - he can walk unaided. And even if he cannot reach that point, just standing up will do wonders for his confidence as well as the attitude of those around him. As Mark Emly, Stanton Vale's headteacher, says: "Every- one sees them as vertical individuals."
So why didn't anyone think of it before? There are many answers - conservatism and the acceptance of traditional practices among them. What was needed was someone to turn the idea into practice, because none of it, inevitably, is quite as easy at is sounds. For a start, because the approach links education with physical movement, it requires a co-ordinated team effort involving school, physiotherapist and parents.
Educational targets, for example, are linked with movement targets so a child's classroom area, and the tasks within it, are organised to make the necessary physical demands.
Most of the equipment is specially designed - and expensive. Typically, it consists of a wheeled frame in which the child can stand, supported by straps (called "prompts" to avoid the implied restraint of "strap"). As the child progresses, the prompts are subtly adjusted, and sometimes removed.
At Stanton Vale a group of parents watch their children moving around the hall. All are delighted with the children's progress. Alec
Holt points out his eight-year-old son Edward, who has a rare genetic defect severely affecting his development, including mobility. He is walking unaided and looking very cheerful. "It's helped him tremendously. He's able to be naughty now - in the park he can run away and look over his shoulder at us. If he was still in his buggy he'd have to go where we wanted," says Mr Holt.
Independence is a key theme for the parents of children whose mobility is restricted. Just having the ability to decide which direction to take across a room means a great deal.
Julie Foulkes, for example, is delighted at the way the MOVE programme has helped her six-year-old son Oliver, who is moving about the hall in a frame. "He can go where he wants, and he can throw a ball to his brother. Just standing up is so much better for him," she says.
Oliver, she explains, "has gone from being immobile to being able to stand and take a few steps. I never thought I'd see him do that."
Mikki Court's son Steven has been on the MOVE programme since it started at the school in 1993. "He could just do limited crawling then," she says. "Now he walks with his frame, and by holding on to our hands at home - when he wants to."
MOVE is managed at Stanton Vale by deputy head Jan Wells, who is at pains to emphasise the necessity for a team approach, and for the programme to permeate the curriculum. "It's not bolted on. It's used to deliver the national curriculum, " she says.
The programme was created in the United States by Linda Bidabe, who, having worked with severely disabled children for many years, became convinced there was a better way. Most descriptions of the programme refer to it as "top down" - the starting point comes from interviewing parents about what they want their children to achieve. This produces such answers as "ride in a car", "eat in restaurants", "get in and out of bed".
From this can be derived a list of target skills, from "maintaining a sitting position" through "walking forward" to "walking down slopes".
These are then carefully defined and tracked, to be achieved through the joint efforts of pupil, parents and the school team. Ms Wells is convinced of the value of this short-circuiting of the traditional developmental approach. She says: "We've tried developmental models for years, but children don't make it through them."
Jenny French, professional director of MOVE Internation al (Europe) provides training and works with schools. She says the programme offers life-long benefits for severely disabled people. In the United Kingdom 75,000 children and more than 400,000 adults up to the age of 60 are so disabled that they do not learn naturally to sit, stand and walk. She talks of regimes "that had children strapped to chairs, and then eventually pushed out of the door to adult centres." Hard research evidence of what MOVE achieves, Ms French points out, is difficult to provide - there are obvious problems in setting up controlled experiments. "But the anecdotal evidence is convincing," she says. Mr Emly agrees. "It's working superbly. I can see radical differences in a short time."
MOVE in Europe is in partnership with the University of Wolverhampton. The organisation runs a programme of courses for teachers and support for schools. Enquiries to MOVE International, Centre for Educational Development. University of Wolverhampton, Gorway Road, Walsall SW1 3BD. Tel: 01902 323066