LOS ANGELES — Tens of thousands of Los Angeles teachers returned to work Wednesday after voting to ratify a contract, ending a six-day strike at the nation's second-largest district.

"Great! It can't be better!" said Helen Han, a kindergarten Mandarin language teacher in Chinatown. "I wasn't really worried because the parents were totally behind us."

Her colleague, third-grade teacher Van Morales, said it was a joy to go back to her students. "It's missed time that we need to make up," she said.

The Los Angeles teachers headed back to work a day after Denver teachers voted Tuesday to go on strike after more than a year of negotiations. While Colorado teachers have the right to strike, the state officials could delay the walkout by up to 180 days.

In Los Angeles, teachers and administrators greeted students with smiles, hugs and high-fives. The return followed days of marches and picketing and a marathon bargaining session that led to a ratification vote Tuesday.

The deal includes a 6-percent pay hike and a commitment to reduce class sizes over four years.

Mayor Eric Garcetti, accompanied by union and school officials, called it an "historic agreement" that will usher in a "new day" for public education in the city.

As the strike ended, the union and district were named in a proposed class-action lawsuit by a teacher who claims union dues are still being deducted from her paychecks in violation of a US Supreme Court ruling.

The suit says Irene Seager revoked authorization for dues deductions after the June ruling that government workers can't be forced to contribute to labor unions, but UTLA contends revocation can only occur during an annual 30-day "window".

The union and district did not immediately comment on the lawsuit.

Elsewhere, the Denver strike vote was not the only other sign of a restive teacher labor force.

In Oakland, California, some teachers called in sick last week as part of an unofficial rally over their contract negotiations, which hinge partly on a demand for smaller class sizes.

Teachers hoped to build on the "Red4Ed" movement that began last year in West Virginia and moved to Oklahoma, Kentucky, Arizona, Colorado and Washington state. It spread from conservative states with "right to work" laws that limit the ability to strike to the more liberal West Coast with strong unions.

Besides the pay raise and class size reductions, the Los Angeles contract adds more than 600 nursing positions over the next three years. Teachers had complained that some schools only had a nurse on campus one day a week.

Additional counselors and librarians are also part of the agreement.

The new contract, which runs until June 2022, also eliminates a longstanding clause that gave the district authority over class sizes, officials said. Many schools will see a class size reduction of about four students in three years — though 90 high-needs campuses will see six fewer students per class during that time.

District Superintendent Austin Beutner said he was delighted the deal was reached. But he hinted financial challenges remain.

"The issue has always been how do we pay for it?" Beutner said. "That issue does not go away now that we have a contract. We can't solve 40 years of underinvestment in public education in just one week or just one contract."

The district maintained that the union's demands could bankrupt the school system, which is projecting a half-billion-dollar deficit this budget year and has billions obligated for pension payments and health coverage for retired teachers.

AP