The CD-ROMs given out to teachers yesterday to get them acquainted with the new citywide curricula for math and reading are an example of the trouble with the contract between New York City and the teachers union. The city, it turns out, has no way to make teachers learn the new curricula over the summer. Teachers, under the contract, get summers off. Totally off.

In negotiating the last contract, Mayor Bloomberg traded a 16% raise to the teachers for 100 extra minutes in the school week. The raise was also widely interpreted as being linked to the deal that won Mr. Bloomberg “control” of the schools. By that it is meant that the mayor won management authority over the city’s public schools, which had been run by a quasi-independent Board of Education with limited public accountability. But as the CD-ROM scenario indicates, the contract provides some serious constraints on the level of “control” that Mr. Bloomberg really has.

In his book, “Breaking Free: Public School Lessons and the Imperative of School Choice,” City Journal’s Sol Stern details some of the more onerous contract provisions. One of them is that principals can’t ask teachers to come in more than one day before classes begin. The administration has gotten around that one this year by stringing together three professional development days at the beginning of the year — even then, it’s hardly the time needed to learn a new curriculum. Other provisions include: teachers not being required to walk children to a school bus, teachers not being required to patrol the lunchrooms or the hallways, and teachers not be ing required to cover extra classes in emergencies. There are also the seniority provisions of the contract. Mr. Stern describes these as resembling a “longshoreman’s hiring hall of the 1950s, with the worker who has the most years of seniority getting the plum job.”

It’s no wonder that charter schools, which are exempt from the contract, see such improvements over traditional public schools. The Knowledge Is Power Program Academy in the South Bronx, established as a charter school in 2000, ranked 17 th in New York City in the eighth-grade reading scores released in May, with 72% reading at or above grade level; that is opposed to an average of 32.5% in New York City. The KIPP Academy meets from 7:25 a.m. to 5 p.m. during the week, for four hours on Saturdays, and for three weeks during the summer. The school has a 213-day school year, compared to the 180 days that most public schools have under the standard contract.

That contract expired on May 31. Mr. Bloomberg is asking to be judged by the voters in a large part on the basis of his success or failure in turning the schools around. The stakes are high, not just politically, but for the children in the system. So, as the mayor negotiates the next contract, we hope he bargains ferociously to win for all the city’s schools some of the flexibility that charter schools have. If Mr. Bloomberg finds firm resistance at the bargaining table, he may want to revisit the issue of school choice. That would make it easier for parents and students to choose schools where it’s not just the students, but the teachers who have required summer reading.