Chicago Public Schools on Tuesday laid out its most concrete plans yet for when in-person learning will start, but also said re-opening is contingent on the spread of COVID-19 stabilizing.

Preschoolers and some special education students will have the option of resuming in-person learning after the holiday break on Jan. 11. But in a survey done in October, only a third of those students’ parents told the school district they are ready to return.

The district’s plan also gives all elementary school students the option to go into classes part-time starting Feb. 1. In the district’s proposed hybrid model, students will go to school two days a week and learn from home the rest of the time. But the school district has yet to survey their parents about whether they will bring them back.

Parents can still choose to keep their children in remote learning, but they won’t be able to change their mind and send their kids back to school for at least a while.

“The decision to begin in-person learning this January will restore their access to high-quality instruction and is the result of balancing our commitment to equity with our current public health situation,” said Mayor Lori Lightfoot in a press release.

Prior to this announcement, school district officials had said they could open up school for classes for the youngest learners and severely disabled students as soon as November.

“We’re in the midst of this second surge right now and there’s no doubt the trends we see are very concerning,” Dr. Allison Arwady, commissioner of the Chicago Department of Public Health, said in a statement “We want to get to a more stable place with community spread before bringing students and staff back to school. Once we do see more stability, even if case rates remain relatively high, I’m confident in-person learning can work and be safely done.”

Arwady said the city and CPS are tracking the spread of COVID-19 in several ways, including how much time it takes cases to double. She said a case doubling time of at least 18 days would indicate that community spread is stabilizing. She said since early October, cases in Chicago have been doubling every 12 days. In July, the city said it wouldn’t teach in-person if the daily case count exceeded 400 — a figure it now far exceeds.

There are no concrete plans to bring high school students back, though officials say they will evaluate the situation in 2021. CPS officials on Tuesday also announced that all high school sports will be suspended after the governor announced a statewide pause on all indoor group sports.

School district officials make the case that private and parochial schools, as well as schools in European countries, have been open and have not been a significant source of COVID-19 spread.

Officials also say they have taken all necessary safety measures and that they will provide regular testing for staff.

But the school district is in an intense fight with the Chicago Teachers Union over plans to bring students back for in-person learning. The union blasted CPS’ latest plan.

“Today’s announcement appears to be based on the mayor’s political agenda, because it sure isn’t based on science,” CTU President Jesse Sharkey said in a statement. “Just unilaterally picking an arbitrary date in the future and hoping everything works out is a recipe for disaster.”

The union contends the school district has not done enough to make sure schools are safe and has not worked collaboratively with them.

They have asked the Illinois Educational Labor Relations Board to go to court to get an injunction to prevent Chicago Public Schools from opening buildings for students until the union and school district work out a deal. But the school district contends it does not have to bargain in order to resume in-person learning.

The school district says enough teachers and staff have said they are willing to return to school buildings in order for preschool students and the special education students to come back. However, the school district still needs to survey elementary school teachers.

Sarah Karp covers education for WBEZ. Follow her on Twitter @WBEZeducation and @sskedreporter.