Schools in Houston and Fort Worth have made significant progress in closing the gap in achievement between white and minority students, according to a survey of big-city school districts released yesterday.

The preliminary report by the Council of Great City Schools showed the two Texas cities were the most successful of 11 school districts cited for their progress in closing achievement gaps, a persistent problem that is receiving greater attention nationwide as state after state has imposed stricter academic standards in the 1990s.

Motivated in part by Texas's system of grading schools on how well students from different racial and ethnic groups perform on standardized tests, Houston and Fort Worth since 1994 have realized gains in minority student achievement with a concerted focus on improving instruction in reading and mathematics. Based on results on state tests given in the elementary, middle and high school grades, Houston has closed the gap between whites and minorities by 40 percent in reading and math, while Fort Worth has reduced its gap in those two subjects as well as in writing by about 35 percent.

Texas Gov. George W. Bush, front-runner for the GOP presidential nomination, has advocated an emphasis on reading and touted the state's school grading system, which is being used as a model for draft House legislation to renew the federal Title 1 remedial program for disadvantaged students. "Even though the [school] accountability system was in place before the governor came into office, he has worked to strengthen and expand it," said Linda Edwards, Bush's press secretary.

"Any time you can get 40 percent change in four or five years in anything . . . you have done pretty good," said Michael Casserly, the council's executive director. The council released the report, based on a survey of 48 urban districts, at its annual conference in Dayton, Ohio, yesterday.

Although their instructional focus has been similar, the two Texas districts have adopted different strategies for reducing the achievement gap, with Houston making district-wide changes designed to help all students and Fort Worth targeting improvements at low-performing schools with large minority enrollments. More than 70 percent of students in both districts are either Hispanic or African American.

School officials in both districts were quick to point out that the narrowing achievement gap was caused by Hispanics and African Americans doing better on the Texas Assessment of Academic Skills, not by whites doing worse. "We did not do this on the back of Anglo students. Their scores went up too," said Fort Worth Superintendent Thomas S. Tocco.

Both districts credit increased teacher training with much of their success. Susan Sclafani, Houston's chief of academics, said that when a survey of middle school math teachers revealed that few had majored in the subject in college, "We brought in college professors and started teaching mathematics to middle school teachers." The district also began holding "math summits" twice a year, where teachers who taught the subject in elementary, middle and high schools coordinated their instruction for the first time, leading to a structured curriculum across the district.

Houston also adopted a new reading curriculum combining what elsewhere have been competing approaches to reading instruction: phonics and "whole language," which is literature-based.

In Fort Worth, Tocco has implemented what he called "hard-hitting" initiatives as a way of "guaranteeing we teach harder and smarter." One innovation has been the assignment of teachers at 25 elementary schools to teach only math to different classes, instead of providing instruction in different subjects to the same class as most elementary school teachers do.

Otherwise, Fort Worth has relied on a methodical but hardly novel marshaling of good principals, well-trained teachers and sound curriculum. "There is no magic bullet," Tocco said.