San Francisco--California's basic-skills entrance exam for teachers goes on trial in federal court Monday, challenged by ethnic minorities who claim the test is a major reason most of the state's teachers are white.

The California Basic Educational Skills Test, or CBEST, arbitrarily closes the schoolhouse door to thousands of qualified Latino, African American and Asian educators, said lawyers for ethnic minority educators seeking to eliminate the test. While non-whites make up 59% of the state's public school students, more than 80% of the teachers are white, said the Hispanic, black and Asian American education groups that filed the suit in 1992.

But state lawyers said BEST requires only a 12th-grade education to pass, and measures the minimum skills and knowledge that teachers and administrators need. They said differences in passing rates were due to test-takers` skills and preparation, not their ethnicity.

CBEST is a multiple-choice test in reading comprehension, writing, and mathematics. It as established by a state law passed in 1982, a time when numerous reports were raising concerns about teacher competency, and many states were passing similar laws. The test is required for a public school teaching, counseling, or administrative credential. It was revised last year to eliminate some questions in higher mathematics, allow more time to take the test, and raise the passing score.

The state says 538,000 people have taken CBEST, 73% have passed on their first try and nearly 85% have eventually passed. Both sides agree that there are marked differences in racial and ethnic groups' passing rates, but disagree on the significance of the numbers. The plaintiffs emphasize the first-time passing rates: 80% for whites, 38% for blacks, 49% for Hispanics and 53% for Asian Americans.