After two years of dismal student scores on statewide standardized tests, Cambridge school officials finally have something to cheer about.

Scores for the grade three Iowa Reading Test released Tuesday showed 59 percent of Cambridge's third graders are "advanced" or "proficient" readers. The jump from last year's score along with exceptional performance from four Cambridge elementary schools--Cambridgeport, M. E. Fitzgerald, King Open and Morse--has teachers and principals beaming with pride.

"We're pleased because we've been focusing on reading and literacy for the past few years," said School Superintendent Bobbie D'Alessandro. "Very clearly, it's showing results on this test. It's phenomenal."

The Iowa tests are given to students in grades three through eight nation-wide. The tests are intended to measure how well a student has learned basic elementary and middle school subjects, such as reading and math.

Last year, third-grade Iowa test results put only 38 percent of Cambridge students at the "proficient" level.

But despite this year's rise, the scores remain slightly below state norms. Thirty-seven percent of third-graders statewide are "proficient" readers and 31 percent rank "advanced"; Cambridge, by comparison, has 31 percent and 28 percent of students in the respective categories.

Lenora M. Jennings, head of student achievement and accountability, said no one in the school system is ready to rest on their laurels.

"We're very pleased with the numbers," she said. "But our job is not done until everyone reaches those numbers."

In the future, the numbers school officials are looking at will be on a different scale--1999 is the last year Massachusetts will give the Iowa reading test. Students will instead take a version of the Massachusetts Comprehensive Assessment System (MCAS) test, and third-graders will be given trial MCAS questions next spring before the test is launched in 2001.

D'Alessandro said she hopes students will shine just as brightly on the MCAS tests, despite poor showings in the past. On the May 1998 tests, Cambridge ranked 168 out of 208 school districts and pulled in its worst scores in the fourth-grade language arts test, with 76 percent of students below the "proficient" mark.

The superintendent sees the Iowa results as an indication that student scores may be on the upswing.

"I'm feeling that the Iowa could be a predictor of how well we do on the MCAS," she said.

Of all the Cambridge schools, Morse Elementary had the best showing on the tests. Morse was one of four schools in the city showing no scores lower than "proficient" and the only Cambridge school to make a list of 19 Massachusetts schools that scored higher than the state average despite serving lower-income neighborhoods.

With MCAS to come and room for improvement still remaining, educators emphasized that they don't use standardized tests as the sole measure of the health of a school system.

"We don't teach to the test," D'Alessandro said. "We really believe in many forms of assessment."