Strong opposition to the Common Core education standards around the country is coming from home-schooling parents.

They’re not required to teach their children using those standards. But many parents are concerned that their use will mean pressure to teach their kids a certain way.

The standards have been adopted in more than 40 states and were pushed by governors who were concerned about the preparation of high school graduates. The standards spell out what math and English skills public school students should master at each grade. But they’ve faced political opposition in many states.

Governors in Indiana, South Carolina and Oklahoma have signed bills to repeal their use.