The Wall Street Journal has the awful details here.

The Ujima Village Academy is one of the best public schools in Baltimore and all of Maryland. Students at the charter middle school are primarily low-income minorities; 98% are black and 84% qualify for free or reduced-price school meals. Yet Ujima Village students regularly outperform the top-flight suburban schools on state tests.

[snip]

Ujima Village is part of the KIPP network of charter schools, which now extends to 19 states and Washington, D.C. KIPP excels at raising academic achievement among disadvantaged children who often arrive two or three grade-levels behind in reading and math. KIPP educators cite longer school days and a longer school year as crucial to their success. At KIPP schools, kids start as early as 7:30 a.m., stay as late as 5 p.m., and attend school every other Saturday and three weeks in the summer.

[snip]

To meet the union demands, the school recently told the Baltimore Sun that it has staggered staff starting times, shortened the school day, canceled Saturday classes and laid off staffers who worked with struggling students. For teachers unions, this outcome is a victory; how it affects the quality of public education in Baltimore is beside the point.

H/T: KP