The Illinois Senate has approved a bill that would require public schools to teach LGBT history.

The measure passed Wednesday on a 34-18 vote, according to The Associated Press.

It mandates elementary and high schools teach a unit studying "the role and contributions of lesbian, gay, bisexual, and transgender people in the history of this country and this State."

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School boards would be allowed to determine how much instructional time is spent on the subject.

If the legislation passes in the House and it is signed into law, Illinois would become the second state to require an inclusive LGBT curriculum.

Last year, California became the first state to use LGBT-inclusive history textbooks.

The bill reflects other current laws that require students learn about other groups such as African-Americans, Hispanics and Asian-Americans.

Some conservative groups pushed back and called on schools to add more dissenting voices from people who oppose “the homosexual movement.”

"The left's motive is what it always is: It is to normalize homosexuality," said Laurie Higgins with the Illinois Family Institute, a Christian organization.

Brian Johnson, the CEO of the LGBT organization Equality Illinois, said last month that the legislation counters the negativity LGBT students already face.

"We think all students are better off when we teach them the full breadth of history," he said. "It makes them more likely to understand that a diverse cast has contributed to our society."