Chicago schools will stay closed through April 20 in an effort to stem the exponential growth of the new coronavirus, Mayor Lori Lightfoot said in a Thursday evening address. 

The school district said moments after the mayor’s announcement that it will seek a one-year waiver from the state to suspend school ratings and spring standardized testing. Under the proposal, ratings from the current year would be carried forward.

“As a result of the significant loss of instruction days this school year, it is necessary for the district to ensure schools and students are assessed fairly based on the academic opportunities that could be provided this year,” said LaTanya D. McDade, the district’s chief education officer. “We will continue to keep educators and families updated on any other potential changes that are warranted given the unexpected challenges we are facing.”

The school closure extension is part of a larger package of emergency measures, including the closure of most of the city’s libraries, and the suspension of evictions, fines, and fees in the wake of the virus’s spread. The school closure extension will impact more than 350,000 students and their families across Chicago. 

The mayor also announced a $100 million economic relief package to support Chicago’s small businesses on Thursday. She stopped short of a shelter-in-place edict but ordered anyone exhibiting symptoms of illness to stay home.  

“Given what we anticipate as the continued upward trajectory of the virus spread, I am announcing now that Chicago Public Schools will be closed through April 20,” Lightfoot said Friday. “We need to give parents and guardians plenty of advance notice about this reality and the ability to plan.”

Related: Live updates on coronavirus and Chicago schools  

She promised that the district would continue to support families through the closures. Chicago Public Schools, though shut for students, have functioned as food distribution sites since March 17. On the first day of closures, frontline cafeteria workers, security personnel, and school administrators handed out 28,000 food packets. 

Chicago first closed schools for two weeks by order of Illinois Gov. J.B. Pritzker, and the two-week closure was one of the shortest time spans among large cities. New York City schools, the nation’s largest school system, are closed through April 20. Boston closed schools until April 27. 

Some states and municipalities are starting to announce more drastic measures. So far, only Kansas and one southern Indiana district have made the call to shutter schools for the rest of the school year. Colorado Gov. Jared Polis said Wednesday that it is “increasingly unlikely” that the state’s schools will return to session this year. California’s governor said something similar Tuesday. And New York City’s mayor earlier this week that it’s possible the closure will “take us through the school year.” 

As districts ponder longer-term closures, they are confronting questions about how to continue learning. Chicago, like many urban districts, is not set up to do districtwide e-learning.

Statewide, two-thirds of Illinois school district leaders say they are not positioned to do online learning. A spokeswoman from the state school board has said leaders are petitioning the philanthropic community to help.

Earlier Thursday, Gov. J.B. Pritzker announced a spike in confirmed Illinois COVID-19 cases to 422 from 288 the day before. The state has reported three deaths so far connected to the virus. 

Tobias Straus, a senior at Lane Tech Senior High School, said he and his fellow students have been speculating about the prospect of a cancelled prom and graduation ceremony, which now seems more likely. 

“I have friends who would be incredibly upset,” he said. “Their grandparents have been looking forward to seeing them walk across the graduation stage for years.”

He said teens have been connecting on social media in an effort to stay upbeat through the closures and the uncertainty the outbreak has brought. 

“I’m ready for this to be over,” he said.