Any way you look at it, students of color aren't doing as well in school as their white classmates. The academic disparities among racial groups are known collectively as "the achievement gap." Each round of test scores puts the problem in sharp focus. It's a persistent, national problem. But recent reports have shown an especially wide gap in Minnesota. There's no single cause or a clear solution. Still, schools are under increased pressure to close the divide. All this week, Minnesota Public Radio is examining the issue. Reporter Tim Pugmire begins our series, The Education Achievement Gap: Minnesota's Embarrassment, with this overview.