Naomi Schaefer Riley:

High-performing charter schools like KIPP, Democracy Prep and Success Academy confront this problem head-on: They not only have significantly longer school days, but also school years.

In terms of math and science knowledge, though, all American kids fall behind over the summer. Columbia economist Howard Steven Friedman found that students in countries with longer school years tend to perform better on standardized tests.

Top-performing South Korea, for instance, requires 220 days of school — 22 percent more than our measly minimum of 180 days.
“When it comes to learning math and science,” Pondiscio explains, “more is more.”
Which makes it particularly disheartening to see that New York City’s new teachers contract may actually reduce the time kids are in school.
Thanks to some convoluted new provisions, at least one Brooklyn elementary school is letting kids out a half-hour earlier, even if it’s not technically shortening instructional time. It gives you a sense of just how stingy the union leaders are with the kids who need classroom time the most.

Of course, the unions are also reason No. 1 why, no matter how much sense a longer school year might make, it’s a distant dream for any public school around here.