As a new school year begins, it evokes idyllic thoughts of yellow school buses ambling through leafy neighborhoods, picking up cheery children and delivering them to their local public schools. It’s calming, peaceful and exactly the kind of imagery that blinds us to the war zone that public schooling often is.

Whether it’s incessant fighting over the teaching of human origins, clashes over controversial books in school libraries, battles over sex education or sundry other flashpoints, our public schools constantly ignite social conflict.

Just mull over the headlines of the past few weeks, and a picture of brawling in the streets begins to shove aside the idealized yellow bus and smiling children.

It was news last week that Texas Gov. Rick Perry, a Republican presidential candidate, telling a boy that no one knows exactly how old the Earth is, and that Texas schools teach both creationism and evolution. That answer — given in reply to gotcha questions the boy’s mother was feeding him — set off a firestorm of commentary and condemnation of everything from Perry, to scientism, to religion to elitism.

It’s easy to see what lies at the heart of this: According to the latest Gallup poll, about 40 percent of Americans believe that “God created humans in their present form about 10,000 years ago.” Meanwhile, “thirty-eight percent believe God guided a process by which humans developed over millions of years … while 16 percent … believe humans developed … without God’s involvement.”

Americans have highly diverse beliefs and values — generally a sign of great health in a free country — but public schools force them to fight over whose values will be taught.

Look at another timely issue — bullying. Over the past few years, in response to several student suicides, people across the nation have sought to stamp out bullying. But a funny thing has happened on the way: Others have objected. It seems once you get past a very black-and-white question — generally, one student cannot physically assault another — there’s suddenly a lot of gray.

Is bullying, for instance, one child writing something critical of another on Facebook? Or is that free speech? What if the commentary threatens no violence but makes its target uncomfortable in school; should school officials be able to intervene? What if school property wasn’t used to post the comments and no questionable behavior has occurred on school grounds?

At the very least these are tough questions, and well-meaning, reasonable people can come up with different answers based on competing values. But districts have to make decisions, and when they do they must sacrifice some basic value — either free speech, or equal entitlement to a free education.

Perhaps no place illustrates how government schooling pits diverse people against each other more clearly than Minnesota’s Anoka-Hennepin district. After a recent string of suicides — some connected to students’ sexual orientations — the district has become the subject of two lawsuits, a federal investigation, and nationwide debate.

Advocates for gay, lesbian, bisexual and transgender students argue that the district fosters bullying by remaining “neutral” regarding sexual orientation. Meanwhile, district parents represented by the Parents Action League assert that moving away from neutrality would unacceptably make children “pawns for social change.”

The result, according to Superintendent Dennis Carlson, has been to render the district a smoldering battleground. And as the Star-Tribune recently reported, “the spotlight isn’t a surprise to Carlson, who recalls the late U.S. Sen. Paul Wellstone telling him that politicos and cultural observers look to the diverse school district as a bellwether not just for the state, but the nation.”

“ ‘That’s why we’ve been chosen for this political battleground,’ Carlson said. ‘[But] it’s not a battle we want to fight. That’s not why we’re here.’ ”

To be ground-zero in sociopolitical warfare, of course, isn’t why any school district is here. Nonetheless, it is inevitably what happens when you force diverse people to support a single system of government schools.

Thankfully, there is a way out: Give parents control of education funds and let them choose options commensurate with their values offered by liberated educators. Instead of making people go to war, let them go in peace.

Watching children go back to school should make us feel good. But it won’t when the education system forces us all into war.