Amid optimism and national acclaim, the Baltimore City school system and its teachers union signed a landmark contract one year ago, tying teacher pay to performance rather than seniority. Now, some in the system are, understandably, growing frustrated that crucial details remain to be worked out and that the system has repeatedly missed deadlines for doing so. But that is no sign that the two sides should give up. There's really no alternative to making the current agreement work, and if that means school system officials and union leaders have to double down on writing the rules clarifying teachers' responsibilities and rewards under the new contract language, so be it.

The city's historic three-year pact was aimed at recognizing the best teachers and giving them financial incentives to boost their students' classroom performance. Top instructors would have a chance to earn six-figure salaries, which will help the city retain talent and stem the drain of high-performing educators to other jurisdictions.

The new pay-for-performance model, which was strongly encouraged by the Obama administration's Department of Education, put Baltimore at the forefront of school reform efforts nationwide. By definition, that meant the city was entering uncharted waters, where no one has all the answers. City and union officials are going to have to work together to iron out the inevitable problems and uncertainties that arise, and to keep in mind that long-term results are what count.

It's understandable that some teachers are concerned about the lack of clarity in the contract language regarding how their performance will be evaluated and what they must do in order to advance their careers and earn more money. Their livelihoods are at stake, and in this new landscape there's no road map they can turn to that will tell them exactly how to proceed.

Will an English teacher who runs a study hall for athletes after school hours earn the same credit for his efforts as a math teacher who organizes a chess club or a social studies instructor who takes her class on a field trip? How about a language arts teacher who attends a professional development conference or a reading teacher who earns an advanced degree?

The school system was supposed to come up with guidelines by the end of June to answer such questions, but many important issues are still being worked out. Perhaps that's only to be expected, given the radical departure from tradition the new contract represents. No one ever said such a fundamental change would or could be completed by the end of the first year, let alone the first six months. School system and union officials are likely to be spending the remaining two years of the contract tinkering with such details.

And that's not necessarily a bad thing, either. For one, it's given teachers a powerful new incentive to come up with ideas on their own about how to engage students in ways that help them perform better in the classroom, which is exactly what we want teachers to be doing. At the same time, it focuses everyone on the day-to-day process of innovation that is the only way to achieve long-term change.

Ultimately, the new contract is only a means to an end, not an end in itself. Its purpose is to move Baltimore's school reform effort to the next level so that city schoolchildren can get the quality education that prepares them for success in college or the work world.

That's not going to happen overnight, but the new contract is at least pointing Baltimore in the right direction. We already know where we want to go and how we plan to get there. Despite whatever detours, wrong turns and traffic snarls may lie ahead, it's far too early to judge whether the linchpin of the city's school reform effort has succeeded or failed.