The co-anchor of ABC’s “20/20,” John Stossel, came out to greet hordes of angry teachers yesterday who gathered outside the network’s studio to protest a segment the program aired about public schools.

Armed with a microphone and television crew, Mr. Stossel, who reported a story that criticized teachers and their union, stood amid hundreds of city educators who stood waving placards and yelling at him to apologize.

One teacher at the protest, which was organized by the United Federation of Teachers, held up a painting of a donkey with Mr. Stossel’s head taped to the animal’s behind.

“This sums up, without using obscenities, what I think of John Stossel,” a health teacher at P.S.123K in Brooklyn, Richard Skibins, said. He was one of hundreds of teachers gathered yesterday afternoon outside the ABC studios on Columbus Avenue and 66th Street.

The protest was sparked by a segment that aired in January called “Stupid in America.” Teachers said it painted them as “lazy” and denigrated the entire public school system. They accused Mr. Stossel of using the show to promote his own pro-charter and pro-school voucher agenda.

“I’m very upset about what you said,” veteran teacher Madeline Moch told Mr. Stossel who talked with a smattering of teachers as an ABC television crew followed him around. She invited him to come visit her classroom in Washington Heights.

“I would love to be invited into classrooms to see for myself,” Mr. Stossel said.

That wasn’t the only invitation he received.

A teacher from Queens invited Mr. Stossel to debate the president of the United Federation of Teachers, Randi Weingarten. He accepted.

During a speech to the assembled crowd, Ms. Weingarten challenged Mr. Stossel to spend a week teaching in a city classroom.

“Teach, John, teach!” the crowd shouted. Ms. Weingarten said the show had depicted teachers as “slackers” instead of “heroes.” She accused Mr. Stossel of trying to give a black eye to teachers and their union.

Ms. Weingarten later handed Mr. Stossel several large brown sacks filled with petitions signed by more than 25,000 educators denouncing the show. Asked about taking up the union on its teaching offer, Mr. Stossel said he would have to check with his network and get back to them.

“Some of my students were very hurt by that,” one teacher leaned over to tell Mr. Stossel about the news program.

“I’m very sorry about that,” Mr. Stossel responded.

Several teachers after the rally said they were pleased that Mr. Stossel came out to hear what they had to say.

“It showed good character, and I didn’t think he had much of that,” teacher Jackie Svatovic said.

ABC News issued a statement saying, “We hope parents will take advantage of the reporting and ask questions of their own school systems, teachers’ unions, and politicians, with the goal of securing better results for their kids.”