Charter school students at Edu-Prize in Gilbert, New Horizon School for the Performing Arts and Noah Webster Basic School in Mesa, Bright Beginnings School in Chandler and the Tempe Preparatory Academy also outperformed many East Valley school districts on the 2004 Stanford 9.

So did many other East Valley charter school students, including those at the Benjamin Franklin charter schools in Mesa, Gilbert and Queen Creek.

Despite the high test scores at Bright Beginnings, principal Syd Hoffman said comparisons based solely on test scores present a skewed picture of a school. She said her students excel at reading and math, but they also do well in other areas that do not show up on national tests - such as music, art and foreign language.

"Test scores are just one measure," she said. "It would be great if we could measure happy kids."

Hoffman said charter school regulators in Arizona have done a better job in recent years monitoring charter schools and making sure new applicants have everything in order before the state grants a charter.

She acknowledged that some East Valley charter schools lag behind the state average in academic achievement, but she said this is often because parents turn to charter schools after their children have failed in traditional public schools or have grown dissatisfied. East Valley charter schools with low Stanford 9 scores did not respond Tuesday to requests for comment.

The American Federation of Teachers study released this month was based on the 2003 National Assessment of Educational Progress, commonly known as the nation's report card. Many Arizona schools administer this test on a voluntary basis in addition to the Stanford 9 and Arizona's Instrument to Measure Standards.