Ethnic-minority children may lose out when they join reception classes because the school's values are so different from those of their homes, a prize-winning research study has found.
Bangladeshi children arrive at school expecting to work, but some fail to make progress because they think teachers want them to play.
Liz Brooker, a lecturer at London university's Institute of Education, found that teachers unwittingly discriminated against Bangladeshi children by assuming that child-centred lessons based on play were suitable for all.
But some Bangladeshi children found them confusing.
Her book Starting school - young children and learning cultures, which has won the Society for Educational Studies' annual best book prize, found evidence of institutional racism from the day children started school.
She followed 16 four-year-olds through their first year at school. All the families lived in the same poor urban neighbourhood with no obvious differences in income.
Eight children were from Bangladeshi families, the rest were "Anglo" children, five white and three African-Caribbean English mixed race.
Dr Brooker, who spent 20 years as a reception teacher, said: "There was nothing discriminatory being done, the children were not being excluded, but within a few days some were benefiting and others were not."
She found that the Bangladeshi children made more progress on average than the Anglo children during their reception year, though they were still behind. But while some were catching up with their Anglo peers, others were falling further behind.
When she first asked the three Bangladeshi children who seemed least interested in learning why they went to school, they surprised her by saying they were there to study. Four months later all three had concluded they were at school to "play". She found they no longer accepted their parents' message that school was about work. They believed that teachers wanted them to play and had not absorbed the unspoken message that the aim was to learn through play.
In contrast, the three children who did best were Anglo pupils whose mothers were aware of how children learnt through play and provided similar experiences at home. Dr Brooker found the staff were aware that differences between home and school would affect children, but believed that the play-based classroom would help to compensate by giving all children the same chances.
She said that this belief assumed that parents and teachers both valued the same abilities in children - such as telling a teacher which toy they want to play with, rather than waiting to be told what to do. Children who had not been brought up with those values could end up losing out.
She said: "I never thought when I was teaching that I could be responsible for children's relative underachievement. But I now assume I was not inclusive."
A Commission for Racial Equality spokeswoman said: "Institutional racism is often unwitting and may be the result of good intentions.
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Friday magazine 6
Starting school - young children and learning cultures, pound;16.99www.openup.co.uk