AEU federal president Angelo Gavrielatos urged parents to talk to schools directly to get detailed information on school performance rather than relying on the website.
"While it is a worthy objective to give parents more information they should not be given information that is misleading," Mr Gavrielatos said.
"National test results were never designed to be used to compare schools and the Federal Government has been repeatedly told they are not accurate enough to be used this way."
"As one of the leading experts in educational statistics Professor Margaret Wu says: It would be irresponsible for the government and education researchers to tell the public that school performance can be judged from information provided on the My School website."
"Schools cannot be compared on the scores of short, snapshot tests completed last May, some in grades with as few as 5 students."
"It is misleading to claim 'like schools' are being compared when important factors like school size, funding and resources and the enrolment policies of a school are not even taken into account. They ignore whether a school has a selective enrolment policy."
Mr Gavrielatos said the primary concern of teachers, parents and principals is that nothing is being done to protect students and school communities from damaging league tables that were now inevitable.
"The Education Minister Julia Gillard says league tables are misleading and make the job of principals and teachers that much harder and yet she is the first minister in our history to provide data that newspapers need to create them," he said.
League tables are now but one click away.
"Ms Gillard cannot sit back and wash her hands of the impact of what she is doing."
"League tables present a crude, invalid and misleading picture of school performance."
"Schools in disadvantaged areas that do not get high scores will be publicly branded as failing schools, despite the wonderful things that may be occurring in them. That unfair branding has a profound impact on students, teachers and parents and makes the job of addressing disadvantage much harder."
"These schools need resources not rankings. It is ridiculous to claim that schools need to be publicly ranked to determine the allocation of resources they need."
"A great deal of information about disadvantage and total resources available to schools is already known to governments."
