In the largest rally since their contract expired two years ago, nearly 20,000 New York City educators from the United Federation of Teachers, parents, and supporters shook Madison Square Garden yesterday, stamping their feet, waving signs, and angrily demanding a new contract with the city that includes raises.

“How can he call himself the education mayor when he’s held up our contract for two years?” the union’s president, Randi Weingarten, said of Mayor Bloomberg. “What’s the excuse now? Scores are up. The money is there. Our members deserve competitive salaries.”

The rally took place one day after Mr. Bloomberg and his schools chancellor, Joel Klein, announced that public school students in the third, fifth, sixth, and seventh grades demonstrated impressive one-year gains on the city’s standardized English and math exams, scoring at the highest levels since the exam was first administered six years ago. The Bloomberg administration attributed the improvement to the recent school reorganization and to the implementation of new comprehensive curriculums in reading, writing, and math.

Several teachers at yesterday’s rally offered a different take on the improved test scores. “They would affect this event more positively if this administration seriously understood who is really responsible for the test scores. It is the hardworking teachers, not any mandated ideas of the Bloomberg administration,” a language-arts teacher for more than 20 years at IS 143 in Washington Heights, Peter Miner, said. “It is as if the mayor sat down with his people and said, ‘Let’s get elected without this contract. If I dazzle this electorate enough, we don’t need the teachers.’ That’s part of the arrogance that I hold him accountable for.”

Other teachers accused the mayor of using the scores as political ammunition and prioritizing West Side and downtown development projects and his own re-election over settling the teachers’ contract dispute.

Four mayoral candidates – Democrats Fernando Ferrer, Gifford Miller, and Anthony Weiner, and Republican Thomas Ognibene – enjoyed an impromptu opportunity to rouse the crowd, tout their education credentials, and jab at Mr. Bloomberg’s schools record. The candidates were introduced and paraded on the stage, but they were not scheduled to speak – until Mr. Weiner grabbed the microphone and told the crowd of his mother’s 30 years of experience as a teacher in the city school system. When Mr. Ferrer attempted to follow with a stump speech of his own, all of the candidates were awkwardly ushered off stage.

Only later in the program did Ms. Weingarten interrupt and invite the candidates back on stage for two-minute addresses. Mr. Miller drew the loudest applause when he recalled his experience last year teaching an eighth-grade social studies class once a week, saying he developed a new appreciation for the importance and difficulty of teaching. “If this mayor had done that just once in his entire life, you would have a contract now,” Mr. Miller said.

The mayor and the chancellor were sent invitations to the event but did not reply or attend. A spokesman for the mayor, Robert Lawson, said in a statement: “Union and special interest rhetoric aside, the facts are that test scores are up, our schools are safer, and we are building new schools and reducing class size through the most ambitions capital plan in the city’s history. After generations of failure, we are finally taking our schools in the right direction.”

Yesterday’s event at Madison Square Garden – not a favorite venue of the mayor’s, because of its owners’ fierce opposition to his plan for the New York Sports and Convention Center – featured entertainment from Richie Havens, among others.