Washington ? Despite unprecedented efforts to improve minority achievement in the past decade, the gap between black and white students remains frustratingly wide, according to an Education Department report released Tuesday.

There is good news in the report: Reading and math scores are improving for black students in public schools across the country. But because white students are also improving, the disparity between blacks and whites has lessened only slightly.

On average, the gap narrowed by about seven points from 1992 to 2007, so that black students scored about 28 points behind white students on a 500-point scale.

The divide between minority and white students is considered one of the most pressing challenges in public education. Experts say it stems from entrenched factors that hinder learning.

More black children live in poverty, which is linked to an array of problems: low birth weight, exposure to lead poisoning, hunger, too much TV watching, too little talking and reading at home, less involvement by parents and frequent school-changing.

The gap exists even before kids start school. But schools don’t mitigate the problem, said Kati Haycock, president of the Education Trust, a children’s advocacy group.