Some schools are "cheating" to ensure their students achieve high NAPLAN scores, forcing children to skip lunch and other school activities so they can train for the test, Figtree dad Dr Justin Coulson claims.
Dr Coulson said students were forced to vigorously practise for the test, which is designed to examine a student's existing literacy and numeracy levels.
"It's too easy for people to cheat, but people are only cheating because the system stinks," he said.
"If you want to know how good your child is doing, don't get your child to sit a test in April and look at the results in September, go and talk to your child's teacher."
NAPLAN results from the previous year are posted on the My School website in March, with the latest round added last week.
Federal Education Minister Peter Garrett last week said the site, now in its fifth year, shone a spotlight on student and staff performance.
"This latest update to the website will help us continue to learn what is working in our schools and where we need to direct our attention and resources," he said.
"It provides parents, teachers and the community with more information about schools than ever before."
Wollongong High School of the Performing Arts principal Dianne Trist said the data received by schools was useful for spotting areas of improvement in individual children, but publishing the resulting information could lead to confusion.
"The NAPLAN gives us good information at a point in time on the particular student for us to make judgments on," she said.
She said students at her school were not trained ahead of NAPLAN.