RALEIGH — A group of Triangle academics pulled up research and data Wednesday as they urged the Wake County school board not to take the final vote to ditch its diversity-based student assignment policy next week.

For instance, Helen Ladd, a professor of public policy studies and economics at Duke University, didn't just predict problems hiring and keeping teachers at some exceptionally high-poverty schools Wake is likely to create under its new plan.

Ladd presented an analysis of statewide numbers that showed such schools have the highest percentage of teachers with less than three years' experience, with lower teacher test scores and with degrees from lower-quality colleges.

"By every measure, high-poverty schools have teachers (and also principals) with weaker credentials than other schools," Ladd said in her presentation at the Unitarian Universalist Fellowship on Wade Avenue.

Professors from UNC-Chapel Hill and N.C. State University also brought the results of years of academic work to a briefing sponsored by the nonprofit advocacy group Great Schools in Wake. They argued against ending the policy of keeping schools socioeconomically diverse, using busing in many cases, to avoid high concentrations of low-income students.

The pro-diversity presentation was made just days before the school board majority is expected to affirm a major change in school assignment policy. When the board meets Tuesday, it is scheduled to vote for a second time to send the system's 140,000 students to community-based schools. The education scholars urged Wake County not to rush into systemwide change without considering some of Wake's strengths - such as specific approaches in some schools that help bridge the academic achievement gap of some minority students. The scholars also warned about potential problems if the changes increase the number of very high-poverty schools.

Kathleen Brown, head of the educational leadership area at the UNC School of Education, and the other academics who spoke Wednesday concede that the Wake system has significant problems under the diversity policy. Notably, there's a persistent achievement gap between students from better-off families and those from lower-income and minority groups.

"Clearly there are issues in our schools, issues that preceded this conversation and issues that will follow it," said Paul Bitting, associate professor in the College of Education at NCSU.

Leaders of the board majority, four of them elected last fall, have said that a reconfigured system could include schools with new concentrations of high-poverty students and require additional resources to keep those schools healthy.

For an academic study, Brown and a colleague identified 24 demographically similar elementary schools in Wake County - those with the lowest and highest achievement gaps between white and minority students. According to the research, the schools followed the same state curriculum and many other practices, but the schools with the smallest achievement gaps shared these similarities:

Leaders recognized and celebrated academic achievement and expected excellence from each child. This included everything from phone calls to parents to making notes on students' report cards, in contrast to a more passive approach at schools with wider gaps.

Principals based their hiring of teachers on skill level more than on personality and offered staff highly specific guidance and feedback, pointing them to additional people or other sources for improvement.

In dealing with the state's mandated curriculum, the schools with smaller achievement gaps "emphasized creativity and depth [and] built upon students' strengths," while schools with larger gaps "remained focused primarily on coverage and consistency."

thomas.goldsmith@newsobserver.com or 919-829-8929