Since 2021, state lawmakers have introduced nearly 400 bills aimed at giving parents, government officials and concerned citizens the ability to challenge or monitor what schools teach about race and gender issues, according to a new report from the free expression advocacy group PEN America.

While many of these laws stop short of directly censoring what is taught in classrooms, the PEN America analysis found many of the proposed bills have had a "chilling effect" on public education.

Educators told the advocacy group they now fear they could be held criminally liable and lose their jobs for teaching "prohibited" concepts.

"Bills with these provisions are frequently being cast as advancing 'parental rights' or 'curriculum transparency,'" the report stated.

But, the nonprofit said, the laws "have an ulterior motive driving them: to empower a vocal and censorship-minded minority with greater opportunity to scrutinize public education and intimidate educators with threats of punishment."

The report analyzed 392 bills introduced in state legislatures between January 2021 and June 2023.

It found some of the proposed legislation would require teachers to post all educational materials on public websites, make it easier for parents to challenge books and allow parents to decide if their child could participate in certain lessons. Other bills would require teachers to report a student's gender expression or sexual orientation to their parents, the analysis found.

Only 39 of the bills proposed have become law across at least 19 states, the nonprofit said.

The report goes on to say, "an additional nine policies were adopted via executive order or incorporated into state-level policy as regulatory measures."

The analysis found Tennessee has enacted nine new laws, the most of any state.

"These bills risk turning every classroom into an ideological battleground, forcing teachers out of the profession, and jeopardizing the future of millions of students," said Jonathan Friedman, director of free expression and education programs at PEN America, in a statement.

Friedman later told CNN the private sector and other entities such as museums and public libraries have a "responsibility to step up in this moment."

"This is a moment where we need to call a lot more of civil society to take action and get involved in the issues," Friedman said.