Want to know how early your son's second-grade teacher has to arrive at school each morning? Whether she hands in lesson plans each week?

Whether she's allowed to spank your son?

A Web site launched recently by the National Council on Teacher Quality promises to shine a light on teachers' working conditions. It gathers the minutiae of union collective-bargaining agreements and state policies for the nation's 50 largest school districts into a consumer-friendly database that allows anyone to compare districts. Together, the 50 districts educate 8 million children — about one in six public school children in the United States — and employ nearly half a million teachers.

The council, a Washington-based research and advocacy group, hopes to expand the database by year's end to include the top 100 districts.

Director Kate Walsh says the site will help parents, policymakers, journalists and others understand how teacher contracts work by giving them access to largely unfiltered information about teachers' workdays, salaries, benefits and more.

"None of us benefits from having our heads in the sand," she says.

Want to find out how many days teachers in Duval County, Fla., work without students in the building? It comes out to 18. In Hawai'i, it's nine. In New York City, it's 5 1/2. In Albuquerque, zero.

Teacher unions say the data could be misinterpreted — unions often agree to contract provisions to comply with local or state regulations, or contracts are hard to compare for other reasons, says Edward McElroy, president of the American Federation of Teachers.

"It is important for the public to realize that labor relations are far more complex than what this database captures," McElroy says. "This is just one layer of a three-dimensional onion."

Bill Raabe, director of collective bargaining and member advocacy for the National Education Association, the nation's largest teachers union, says he's concerned that users could draw "erroneous conclusions" from what they read — for instance, if a contract is silent on class size, it doesn't mean that the union didn't address it. The issue could simply be dealt with by state law.

"The contract is really just a piece of the picture," he says.

The database actually could aid teachers in a few districts during their next round of contract talks: What better way to show they're getting a raw deal, comparatively speaking?

"It's a whole field that's largely unexplored," Walsh says.

The contracts are public documents, but they're not always accessible, says Andrew Rotherham, co-editor of the 2006 book "Collective Bargaining in Education."

He says he was "stunned" at the lack of information available in most districts. Walsh's database, he adds, "moves you past the sort of anecdotes" that typically frame teacher issues.

"This transparency is good for everyone."