Students enrolling in college-level Advanced Placement classes at Palo Alto High School this semester had to sign on a new dotted line — a contract agreeing to take California standardized tests.

The new contract is a local solution to a problem districts statewide are grappling with: how to get students to take tests they are technically allowed to skip.

Paly has joined Gunn High School in requiring students enrolling in Advanced Placement (AP) classes to take state tests known variously as Standardized Testing And Reporting (STAR) tests or California Standards Tests (CSTs).

The federal No Child Left Behind Act of 2001 uses participation in such tests to calculate whether schools adhere to strict standards — or face penalties. State law, however, allows parents to request an exemption from STAR exams for their children.

The STAR tests measure cumulative knowledge in subject areas at the end of the year.

They can consume up to 10 hours or two days of a student's time and disrupt school scheduling, especially in classes taken by both juniors and seniors, district Director of Assessment and Evaluation Bill Garrison said.

In prior years, parents have complained about the slew of tests. Students have labeled the simple state exam less important than the college-credit-conferring AP exams administered by the College Board.

But 95 percent of students in each high school must take state tests to meet federal requirements, Superintendent Kevin Skelly said.

Gunn instituted the rule linking STAR tests to AP courses for its 2006-2007 academic year.

Participation in STAR tests rose to 98 percent last year, according to Principal Noreen Likins. That's up from 93 percent in 2006, according to the California Department of Education's Web site.

But at Paly, many students have opted out of state tests to focus energy on tougher AP exams, which take place around the same time in May, Principal Jacquie McEvoy said.

Only 73 percent of juniors participated in the STAR tests last year, she said. The school's average participation in the English-Language Arts test was 85 percent, according to the state Web site.

Many districts across the state are struggling with participation rates, even throwing morning breakfast parties to encourage students to take the tests, according to education-law expert and Stanford Law School professor Bill Koski.

Linking STAR tests and AP courses is legal as long as schools offer a way for students who don't take the STAR tests to still take an AP course, he said.

Palo Alto Unified will require students who opt out to write a paper or otherwise prove readiness for the AP course, Skelly said.

"There's a mismatch between stakes for kids and schools on the CST tests. ... Schools need to meet that percentage requirement," he said.

The school district failed to meet percentage requirements in particular student subgroups, including Latino and black students and special-needs students, in 2004 and 2006.

Districts receive a federal warning the first time, so Palo Alto has escaped with a wrist-slapping so far.

But if the district's rate — calculated from the rates of each school — dips below 95 percent too often, federal representatives could visit the district to assess problems and force administrators to draft an improvement plan, Garrison said.

The district is under scrutiny because it accepts Title I federal money for disadvantaged students, he said. Paly and Gunn do not receive such funds, so they would not be penalized, he said — but other schools in the district could be.

Participation is used to calculate state and federal school ratings, or Academic Performance Index (API) and Adequate Yearly Progress (AYP), respectively.

There is a glaring irony in the ranking system.

Palo Alto's stellar students score among the highest in the state on standardized tests such as the AP, giving schools top-notch ranking. But those same high-achieving students lower the schools' API and AYP rankings when they opt out of state-run tests to study for APs.

The new rule will help rankings accurately reflect schools, Garrison said.

"We like to see ourselves ranked up there with the best districts in the state, and unless we have adequate participation we're not going to be in those rankings," he said.

The score data also allow students to figure out whether they are qualified for AP-level classes, McEvoy said, a sentiment echoed by Likins.

Both principals said it can get tricky to find room for students who drop out of classes they realize are too tough only after the year has started.

Last year, students who dropped out of AP English classes found there was no room for them in standard English classes, meaning they had to wait a year to fulfill their English requirement, McEvoy said.

The new rule is more about measuring student ability than meeting participation requirements, she said.

But education-law expert Koski said that the unchallenging STAR tests are unlikely to be a good measurement of coursework preparedness.

"As far as I'm concerned, the STAR tests are not extremely good indicators of one's readiness or qualification for AP courses. ... The metric for AP classes is grades and teacher recommendations and other sorts of things," he said.

To lighten the new rule's burden, McEvoy and Likins said the schools are making an effort to schedule AP tests before the STAR tests. Students don't need to study for STAR tests, meaning they can relax after APs are finished, Likins said.

Student and parent reaction to the new rule was initially indignant, but was followed by acceptance once the threat of federal sanctions was made clear, they said.

"There's a lot of juniors who think it's a waste of time still, so they think it's not really fair they have to take it," Paly sophomore Olivia Diamond said. But students don't object once they learn about possible federal sanctions, according to Diamond, who is also the student government's sophomore representative to Paly's Site Council.

Gunn parent Martha Bowden said it's hard to argue with the new rule.

"[Critics] pretty much lose their argument because no one in Palo Alto wants to withhold funding for our students," said Bowden, a PTSA member and liaison to the Site Council. Neither, she said, does anyone want the federal government getting involved in the district.