A Southern California school board on Friday adopted a social studies curriculum that includes gay rights that was approved by parents and teachers after initially rejecting it.

"Fortunately, now students will receive the basic materials needed to learn," said Gov. Gavin Newsom in a statement following Friday's vote.

Newsom previously warned that the district could be sanctioned if it didn't use the state-approved curriculum.

The curriculum in question is titled "California's Cultural Contributions," board member Allison Barclay of the Temecula Valley Unified School District told CNN.

"Within the lesson, there are several sections, such as artists, architects, writers, educators, discussing Californians who made substantial contributions in these areas," she said. "Under the heading 'Protests,' one paragraph discusses gay rights in California and under the heading 'Court Cases,' there are two paragraphs that discuss the court cases that allowed gay marriage in California."

She said a supplemental resource lists Harvey Milk, a gay rights activist and politician who was assassinated in 1978, along with San Francisco Mayor George Moscone. Milk was believed to be the first openly gay person elected to public office in California.

"There is no mention of Harvey Milk in the textbook that I know of," she said. "He is listed in a supplemental section titled 'Biographies' where there are several hundred short, age-appropriate biographies of historical figures."

The board voted 3-2 on May 16 to reject the curriculum, with some board members claiming there was not enough parental involvement in the creation process and making comments attacking Milk.

Parents at a June public hearing spoke against the rejection of the curriculum, which is for grades 1-5.

"This has never been about parents' rights," Newsom said. "It's not even about Harvey Milk -- who appears nowhere in the textbook students receive. This is about extremists' desire to control information and censor the materials used to teach our children."

Newsom said the state's Justice and Education departments were investigating.

States across the country have increasingly tried to ban topics such as LGBTQ rights. At least 491 anti-LGBTQ bills have been introduced in state legislatures, according to the ACLU.