Washington ? Sex education teachers must present abstinence as the preferred behavior for unmarried people under a bill signed Tuesday in Madison by Gov. Jim Doyle.

The legislation means teachers must emphasize that refraining from sex before marriage is the most effective way to prevent pregnancy and sexually transmitted diseases. A spokesman for the governor, a Democrat, said most Wisconsin school districts already take that approach.

Republican Sen. Mary Lazich, the bill’s sponsor, said sex education teachers can still teach about birth control but must emphasize that abstinence is the only 100 percent effective method to avoid health risks.

The bill takes effect July 1.