ANN ARBOR, Mich. — Graduate students who teach at the University of Michigan returned to classes Thursday after voting to end a nine-day strike.

The Graduate Employees’ Organization, which represents about 2,000 students who teach or assist, says it achieved “critical progress” on childcare options during the coronavirus pandemic, testing protocols and concerns about campus police operations.

The union says the vote Wednesday was 1,074-239, ending a strike that began Sept. 8.

The deal ends legal action taken by the university, which sued this week to try to end the strike.

“By withholding our labor, building coalitions, and making our power impossible to ignore, we forced the university to give us an offer with substantive progress toward a safe and just campus,” the union said.

The university said the strike disrupted many online undergraduate classes taught by graduate students.