Here’s an assignment for every college or high school teacher of journalism, politics, marketing, or ethics.

Make your students watch Bill Moyers Journal: Buying the War, a 90-minute documentary on the culpability of the news media in the Bush administration’s run-up to Iraq. PBS airs it on Channel 2 at 9 p.m. tomorrow and on Channel 36 at 11 p.m. Sunday.

In fact, every American should watch it, especially those, like me, who naïvely bought into a war sold on false pretenses and are outraged by its folly.

Moyers details how top government officials, zealously pursuing an agenda whether facts fit it or not, systematically worked to dupe journalists and the citizenry. Worse, the media — The New York Times and Washington Post, the major networks, and most especially the cable news/talk shows — often functioned as cheerleaders. They spread the message, which they certainly failed to challenge, that Saddam Hussein had weapons of mass destruction and that there was an Iraq-al-Qaida link.

Dan Rather tells Moyers, “I don’t think there is any excuse for, you know, my performance and the performance of the press in general in the roll up to the war. There were exceptions. There were some people, who, I think, did a better job than others. But overall and in the main there’s no question that we didn’t do a good job.”

Moyers explores several reasons, notably an excessive or misguided sense of patriotism, a reluctance to break with the pack and be proven wrong, and a lack of curiosity or energy needed for digging out mid-level sources who could expose the party line.

Bush figures such as Dick Cheney loom as evil geniuses — for example, leaking to The Times a questionable story about Iraq’s alleged plans for a nuclear bomb and then going on TV and citing The Times as an authority.

Moyers talks with such figures as NBC’s Tim Russert and Washington Post media critic Howard Kurtz, and several authors. There’s lots of file footage of Bush, Cheney, Colin Powell, etc., but no fresh interviews with them and few with anyone you’d consider a formal spokesman for a news organization.

It’s a documentary with a point of view, but one worth mulling.

And, as Rather says, some journalists did shine. Moyers focuses on Knight Ridder newspapers’ Washington bureau for doggedly digging and challenging the Bush line. But those papers, spread around the country, didn’t have the cachet or influence of the New York and Washington outlets.

The words of John Walcott, Knight Ridder’s bureau chief, are haunting — and instructive.

He says, “Many of the things that were said about Iraq didn’t make sense. And that really prompts you to ask, ‘Wait a minute. Is this true? Does everyone agree that this is true? Does anyone think this is not true?’ ”

And, “A decision to go to war, even against an eighth-rate power such as Iraq, is the most serious decision that a government can ever make. And it deserves the most serious kind of scrutiny that we in the media can give it.”

Walcott also says that everyone wants to support America’s soldiers. “And everyone should be behind them. The question for us in journalism is, are we really behind them when we fail to do our jobs? Is that really the kind of support that they deserve? Or are we really, in the long run, serving them better by asking these hard questions about what we’ve asked them to do?”

Much on television is junk. I’d call Buying the War must-see TV.

M. Charles Bakst is The Journal’s political columnist.

mbakst@projo.com