Tormenting EU immigrants was deemed acceptable "as it is perceived as having no relation to racism", Chris Keates, general secretary of NASUWT, told a conference on Monday.
It is thought that media scare stories - such as The Sun's "Polish builders nicked my flat" - have whipped up anti-Polish feeling.
Alexandra Podhorodecka, of the Polish Education Society, said: "In the worst cases we see pupils bullied, extremely unhappy, and developing discipline problems, whereas in Poland they may have been high achievers.
"They are made fun of because of their lack of English and also because they are unused to a multicultural society and may appear racist. But they aren't racist, just unfamiliar with the situation."
She added that schools could help by using Polish signs and developing links with local Polish Saturday schools.
John Hughes, head of Victoria junior in Wrexham, said local authority support was important.
"We get language resources from the LEA and have a Polish teacher who comes in and works with students," he said.
The Home Office has announced pound;400,000 funding to improve Eastern European children's English. About 80,000 Eastern Europeans arrived in Britain in 2005. This year, 11,000 enrolled in British schools.
Dr Jan Mokrzycki, president of the Federation of Poles in Great Britain, was confident that pupils would be accepted given time.
"I came to this country with no English, but once I had improved my language skills I became one of the lads," he said.