Some of England's most disadvantaged children start school in nappies, unable to speak or recognise their own name, creating a "permanently disadvantaged" generation, a damning study has revealed.
There is "heart-breaking" evidence of children and young people trapped in "severe disadvantage" a social think tank has claimed, with poor white boys at the bottom of the heap.
The study, by the Centre of Social Justice (CSJ) looked at GCSE performance and found that white boys on free school meals - a key measure of poverty - perform "much worse" than other deprived groups.
Last year, just 26% of poor white boys gained at least five Cs at GCSE, including English and maths, compared with 40% of poor black boys, and 63% of all other pupils. Overall, over two in five pupils - about 228,500 in total - do not score at least a C at GCSE in English and maths, it added.
The research suggests some of England's poorest children have had such abysmal experiences in their early years that they are not ready to start learning at age five, and could be permanently disadvantaged.
In a number of cases, youngsters are years behind their classmates when they begin school, and can act as if they are 12 or 18 months old.
The study, which examines education in England between 2007-12, argues that too many children are seeing their education suffer because of the disadvantage they face in their home life.
One head teacher said that it was very common for youngsters to start school unable to cope, with three-year-olds who "commonly act like 12 to 18-month-olds".
"'They don't even have the concentration to talk and say an answer in any kind of sentence," she said. "We've had children that don't answer to their name. They don't recognise their name...they're not toilet trained."
The study lays blame on parents, saying that part of the problem is that they are not aware of the key developmental milestones their child should meet: "These children are starting school drastically behind the levels of development expected of their age."
The findings add: "The early years experiences endured by these children have been so abysmal that they begin compulsory schooling absolutely not ready for learning and, potentially, permanently disadvantaged."
Teachers reported that they are increasingly expected to deal with basic needs, such as potty training, and in some school teachers carry disposable gloves because pupils routinely need help going to the toilet.
Sir Robin Bosher, chair of the working group that drew up the report, said that in each class he sees, about one in 10 children are "so unsociable that they hurt others, adults and other young children" because they have had no practice at being sociable.
One headteacher told the think tank: "In the last three years we have had to toilet train children who came to school in nappies at age five. Parents ask me how we managed to do it. Many of them just can't be bothered, they think it's our responsibility to do it for them."
As a result, teachers are spending time teaching young children "basic necessities" that they should have mastered before they started school, which cuts into teaching time.
"Considerably more needs to be done both to help disadvantaged young people before they arrive at primary school and to offer them support once they arrive. A system in which some children are effectively four years behind some of their contemporaries by the age of five will always struggle to help those children reach their full potential.
There are signs of children being behind in assessments made at the age of five, the CSJ said.
It cites figures which show that one in eight five-year-olds (12%) cannot write their own name or other words from memory, while 6% of boys of this age do not know that print is read from left to right and top to bottom.
The gap at GCSE between poor white boys and other pupils is now 0.5 percentage points wider now than in 2007/08, the CSJ said.
Sir Robin, who is also director of primary education at the Harris Federation of Academies, said: "Educational failure is too common in our current system. It affects disadvantaged children and makes reform urgent. This is about social justice. We need to do more to make sure all children are given a good education."
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