How to deal with autism should be a mandatory part of initial teacher-training programmes to ensure all children have access to the right education, according to a leading charity.
The National Autistic Society Cymru this week called for more support and better access to provision for children with autism and related conditions.
It launched the campaign - its first in education - at the National Eisteddfod in Swansea.
One in 110 children have autism, so all teachers should expect to teach a child with some form of developmental disability, according to NAS Cymru.
But despite its prevalence, there is currently no requirement for trainee or practising teachers to undertake any training in autism.
The charity says more than a quarter of children with the condition have been excluded from school because of lack of awareness and understanding.
More than two in five children with autism have been bullied, and more than half are not even in the right school, it says. It has now made an awareness-raising film for teachers to help them deal with the disability.
Liz Withers, NAS Cymru policy officer, said educational provision for children with autism is patchy, with support often dependent on the dedication of individuals.
"It depends on where you live and the parents' ability to fight for the right support," she said. "As a bare minimum we would like to see autism training for special educational needs co-ordinators (SENCOs).
"But we would also like to see autism training incorporated into initial teacher-training. If it isn't mandatory how can teachers be expected to support children and know about practical techniques?"
With 27 per cent of children with the condition in Wales forced to attend a school outside their area, the Make School Make Sense campaign is also demanding better access locally to a range of mainstream and specialist educational provision, including resource bases attached to schools, specialist schools and outreach support.
Specialist teacher Maria Prosser runs a special unit attached to Cathays high school in Cardiff, funded by the local education authority. The unit will accommodate 10 pupils from September, but Mrs Prosser says there is more demand for the facility.
"We offer a tailored and flexible approach and each child has a different schedule," she said. "These children need understanding and they need to feel secure. They look like any other children, but they are often misunderstood as being rude or naughty.
"We teach them social skills such as how to hold a conversation, about body language, and how to use their own voice. We also teach them basic skills like how to order coffee in a cafe or how to use public transport."
Diana Brooke's seven-year-old son Henry was diagnosed with Asperger's Syndrome when he was three. Despite the trauma of dealing with Henry's behaviour (he used to scream all the time), he was able to start full-time school at five with one-to-one support in a mainstream setting in Bangor.
"Henry can memorise the codes on locked doors so you have to watch him all the time. But he has the best of both worlds being integrated with other children and also having the one-to-one support," said Ms Brooke.
For mum Marie James, however, the process of getting the right education for her son Trystan in Carmarthenshire was a different story, especially as he was Welsh-speaking. Trystan, now 19, has autism and epilepsy. He did not start secondary school until he was 14, following three years of negotiation and two special educational needs tribunals to secure the right provision.
Mrs James said: "We encountered problems at every transition stage. There was no continuity, and had we not stood our ground and fought for what he needed, he would not even have had an education.
"My heart goes out to the families now trying to get provision for their children."
Gary Brace, chief executive of the General Teaching Council for Wales, said the Assembly government's new standards for qualified teacher status do not specifically refer to autism.
However, they "do highlight the responsibilities trainee teachers will have to identify and support all pupils with special educational needs".
He said: "There is always going to be a delicate balance between listing specific types of special need in the standards, and referring to them generally."