If school teachers want free copies of “An Inconvenient Truth” to show students, producers have 50,000 DVDs they’re eager to give away.

In fact, therein lies the problem. Exec producer Laurie David has been engaged in a highly visible brouhaha with the National Science Teachers Assn. because they wouldn’t accept the 50,000 copies to distribute to their members.

Their reason: They have a policy of not endorsing a particular project. In other words, thanks, but no thanks.

“I never in a million years thought this would happen,” says David, a well-known environmentalist. “It made no sense to me.”

So David wrote an op-ed piece in the Washington Post in which she notes, among other things, that the NSTA has accepted contributions from ExxonMobil, Shell and the National Petroleum Institute. The teachers association even distributed a Petroleum Institute video called “You Can’t Be Cool Without Fuel,” which David calls “a shameless pitch for oil dependence.”

The NSTA denies that its contributors influence curriculum, and says while it does get contributions from the energy industry, that coin makes up just 3.77% of its budget. It no longer has ties to the Petroleum Institute and says it has “no record of distributing” their video. But in a project funded by Conoco Phillips, it did produce a science video series called “Search for Solutions” that was sent to 20,000 teachers.

The NSTA says it offered David other ways to promote “Inconvenient Truth,” but David says she hasn’t heard from them.

Rather than offer the DVDs to another group, Participant Prods. is offering it directly to teachers via www.particpant.net through Jan. 18 on a first-come, first-served basis. More than 1,000 were ordered the first day they were available.

Borrowing a bit of green-speak, David says, “It is the cleanest, fastest way to get them out.”