As schools hold pep rallies to motivate students for the latest round of standardized tests, California's education department has added to the testing mania, releasing rankings based on last spring's performance.

Public school rankings, which are released each spring, range from 1 to 10, with 10 being the highest. The rankings are evenly distributed by school level; in other words, 10 percent of elementary schools in California earn a 1, and 10 percent earn a 10.

In some districts -- including Albany, Castro Valley, Dublin, Pleasanton and Piedmont in Alameda County and Acalanes Union, Lafayette, Moraga and San Ramon in Contra Costa County -- every school was ranked in the top half of the statewide heap, with a 6 or higher.

In less affluent areas, the rankings weren't as strong, or as uniform. In Hayward every district-run school was ranked a 5 or below, while the city's two charter schools were ranked 9 and 6.

Rankings in Mt. Diablo district schools in Contra Costa County ranged from 1 to 10. Six of its schools were among the lowest-achieving in the state, with a ranking of 1, while seven campuses ranked at the very top.

Oakland schools showed a similar spread. Eleven of the 127 schools with rankings -- including independently run charters -- were ranked in the top 10 percent of all schools in the state. But 46 of the city's public schools, more than one-third, ranked in the bottom 10 percent.

Montera Middle School in Oakland, which was recently recognized as a California Distinguished School for raising test scores and closing the achievement gap, received a statewide ranking of 8. When compared to a small group of schools with similar demographics, it was ranked a 9. Last year, it ranked 7 in both categories.

Montera's principal, Russom Mesfun, noted that rankings are just one piece of data, and that other measures are more useful to educators for improving student achievement. Still, he said, "We like to know how our students fare compared to other students in other schools."

The rankings are based purely on a state measure called the Academic Performance Index. The API, as it's more commonly known, is a single score from 200 to 1,000 calculated from a host of standardized tests taken during a school year. Schools received their original API scores last fall and a slightly adjusted number this month, based on tweaks to the formula.

The state has set a target API score of 800 for schools, to show student proficiency in math and language arts. In general, schools ranked 6 or above met or came close to this goal.

To see Academic Performance Index scores and rankings for school districts and schools, go to the California Department of Education's website, www.cde.ca.gov/ta/ac/ap/index.asp and click on "2010 API school reports."

Staff writer Theresa Harrington contributed to this report. Read Katy Murphy's Oakland schools blog at IBAbuzz.com/education. Follow her at Twitter.com/KatyMurphy.

school rankings, explained
California's public school rankings range from 1 to 10, with 10 being the best. The bottom 10 percent of elementary schools in the state receive a 1, and the top 10 percent receive a 10. Statewide rankings are based purely on test scores (the Academic Performance Index, or API). "Similar schools" rankings compare the scores of each school to those of 99 others with similar demographic profiles. You can find the 2010 Base API report on the California Department of Education website, www.cde.ca.gov/ta/ac/ap/index.asp.