“It’s important for us right now to educate Californians about what the bill does and does not do,” said Rebekah Orr, a spokeswoman for Equality California, a leading lesbian, gay, bisexual and transgender rights advocacy group in California. “We want to be clear that this bill is about teaching historical figures and not just LGBT people.”

The new law also requires California public schools to teach the contributions of disabled people.

Orr said Equality California and its partners are prepared to fight the referendum if it qualifies for the ballot.

Many conservatives opposed the law, saying it would teach children to accept homosexuality. The law has drawn criticism from some churches and conservative groups that argue such instruction would expose students to a subject that some parents find objectionable.

California law already requires schools to teach about women, African Americans, Mexican Americans, entrepreneurs, Asian Americans, European Americans, American Indians and labor. The Legislature over the years also has prescribed specific lessons about the Irish potato famine and the Holocaust, among other topics.

The new law requires the California Board of Education and school districts to use textbooks and other teaching materials that cover the contributions and roles of sexual minorities.

The legislation leaves it to local school boards to decide how to implement the requirement. It does not specify a grade level for the instruction to begin.

A telephone message left for the bill’s author, Sen. Mark Leno, D-San Francisco, wasn’t immediately returned. His office said the senator was out of town for the Legislature’s summer recess.

Assemblyman Tom Ammiano, D-San Francisco, who carried the bill in the Assembly, also was out of town.