The federal judge's message to an assembly of social studies students at a Virginia high school seemed straightforward: Courts too often meddle in the affairs of private commerce.

The senior appellate judge, Douglas Ginsburg, was talking about the Constitution, telling students how the courts got it wrong by ruling that the commerce clause gave the federal government authority to regulate the cats that roam author Ernest Hemingway's former home in Key West.

"The Framers didn't design an almighty federal government that could reach down right into your backyard," the conservative judge said on a video shown during the presentation.

Ginsburg's appearance at Justice High School was a collaborative project between Fairfax County Public Schools and a group called, which provides educational materials and videos to students across the country.

Izzit's materials have a decidedly libertarian outlook, though that's not always immediately apparent to the teachers who download their free content. A video that questions the rationale for minimum wage laws is under math, for example.

Another video, called "Unstoppable Solar Cycles," downplays man's role in climate change. The video comes with a quiz in which the correct answer is that man "plays a small part in global warming."

Another, called "I am Human," questions "America's historical obsession with race" with criticism of former President Barack Obama for choosing to identify as African American rather than biracial.

Fairfax County schools, on the outskirts of Washington, D.C., defended its collaboration with Izzit.

"Izzit is an educational nonprofit that specializes in creating free, standards-aligned content for educators that fosters critical thinking and respectful debate," the school system said in a statement.

Critics, though, say Izzit extols a right-wing ideological perspective.

Samantha Parsons, who works for UnKoch My Campus, said Izzit's work fits with the agenda of the Charles Koch Foundation, which has given hundreds of millions of dollars to colleges in recent years to bolster what Parsons and others have said is an effort to promote right-wing ideology on campuses.

She said Izzit, like the Kochs, uses words like "liberty" and "freedom" to mask its right-wing agenda.

"It's Koch-speak," Parsons said of the buzzwords for policies like deregulation, tax cuts and free market supremacy.

Izzit President and Chief Executive Rob Chatfield said Izzit advocates a distinct philosophical perspective. He was reluctant to categorize it as conservative or even libertarian, because he said those terms carry a political connotation that Izzit has no interest in promoting.

"It's that people who are free tend to be happier, wealthier," he said. "If that's the underlying theme that students pick up on, we've done our job."

Tax records show the Koch Foundation gave $83,000 in 2016 and 2017 to Izzit's parent company, the Erie, Pennsylvania-based Free to Choose Network, according to tax documents,

Chatfield, though, said Izzit itself has never received direct funding from the Koch network and primarily gets its funding from "self-made entrepreneurs."

Izzit, founded in 2006, says its goal is to "help educators teach the next generation about the ideas, institutions, and benefits of a free society." More than 300,000 teachers — most in public schools — across the country use its materials, Chatfield said.

The teacher who coordinated the Virginia school's participation in the project, Eric Welch, said in an email that "there was nothing, absolutely nothing that Judge Ginsburg brought up that was controversial or politically motivated," according to documents obtained under the state's Freedom of Information Act.

Bias, though, is in the eye of the beholder, said India Meissel, a history teacher in Suffolk, Virginia, and past president of the National Council on Social Studies. She said some teachers might use Izzit material and see a need to balance it out with a different perspective. Others might see it as right down the middle and and ready for use as is.

"A good teacher presents both sides," she said, and lets students develop their critical thinking to make up their own minds.

Rachel Colsman, a teacher at Durango High School in Colorado, said there are precious few supplemental resources, particularly free ones, to provide content for social studies teachers.

She said she does not perceive an ideological skew in Izzit's materials and thinks it does a good job of engaging students and prompting them to think critically, even if they don't agree with the perspectives. She cited the "I am Human" video as one in particular that "raised some hackles," but she said that's OK.

"Teaching students how to have a reasonable dialogue without getting offended is such a lost art," Colsman said.

Chatfield said he's proud of the "I am Human" video because it takes on a controversial topic that often gets overlooked. He acknowledged that the criticism of Obama's personal choices on racial identification, which comes from one of the people interviewed in the video, goes farther than he would. He said what's important is not the opinion itself but the opportunity to spark a conversation.

Chatfield offered only a minimal defense of "Unstoppable Solar Cycles," saying the video is old and was put out in response to the notion that man-made climate change is settled science.

"If anyone says that something is settled, I want to question that," he said.