Two examples of recent Don't talk about X in classrooms" state laws/legislation:
Florida: Wikipedia's LGBT rights in Florida; HB 1557/Parental Rights in Education/"Don't Say Gay" bill (2022) says:
In March 2022, the Florida Legislature passed House Bill 1557, Parental Rights in Education, often referred to as the "Don't Say Gay" bill by its opponents. Governor of Florida Ron DeSantis signed the bill into law on March 28, 2022. The law prohibits classroom instruction on sexual orientation or gender identity from kindergarten to grade 3 in Florida public school districts, or instruction on sexual orientation or gender identity in a manner that is not "age appropriate or developmentally appropriate for students" in any grade. The preamble of the law also mentions "classroom discussion" of these topics, dividing legal scholars if that would be included within the scope of the law. It also allows parents and teachers to sue any school district if they believe this policy is violated, with school districts covering the cost of the lawsuit. The bill additionally prevents school districts from withholding information about a child’s "mental, emotional, or physical well-being" from their parents. Due to the "Don't Say Gay" nickname, some commentators and social media users thought the bill banned mentioning the word "gay" in school classrooms, though the bill does not actually mention the word "gay" or explicitly prohibit its use.
Alabama: Al.com's April 07/08, 2022 Alabama legislature passes surprise ‘Don’t Say Gay’ amendment, transgender bathroom restrictions says:
The Alabama legislature passed its own version of Florida’s “Don’t Say Gay” law Thursday after a surprise amendment to a transgender bathroom bill.
Thursday morning, the last day of the legislative session, Sen. Shay Shelnutt, R-Trussville, introduced an amendment that would prohibit classroom instruction or discussion on sexual orientation or gender identity for grades K-5.
“We don’t think it’s appropriate to talk about homosexuality and gender identity in schools, they should be learning about math,” said Shelnutt of the amendment.
The amendment’s language mirrors a new Florida law, which applies to K-3 grades. Florida’s Gov. Ron DeSantis signed a law, widely called the “Don’t Say Gay” bill, last month that said “classroom instruction by school personnel or third parties on sexual orientation or gender identity may not occur in kindergarten through grade 3 or in a manner that is not age-appropriate or developmentally appropriate for students in accordance with state standards.”
The original bill, Alabama’s HB322, sought to require public school students to use restrooms and locker rooms designated for the sex shown on their birth certificates.
Question (not limited to LGBTQ/gender):
Question: Are "Don't talk about X in classrooms" state laws a relatively recent phenomenon in the US?
I'm not asking about legislation that's simply about curriculum in some way, but only about legislation that specifies clear, well-defined topics and makes it illegal for teachers to allow discussions about them in public school (or otherwise) classrooms.
Is this a fairly recent phenomenon, say mostly within the least five or ten years, or is there a long tradition of state legislatures making discussions of certain topics in classrooms explicitly illegal in the state?