Partial in-person learning is set to resume on April 19, but the union is concerned about the rate of infections among the younger population, which continues to increase.
"It's critical, we believe, that there be some plan for vaccinating high school age students, who are in many cases eligible for the vaccine, and their family members," said CTU President Jesse Sharkey.
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In addition, teachers said, finding the right scheduling breakdown between in-person learning and at-home instruction is crucial to maintaining safety.
"We can't have 2,000 kids running through the buildings trying to grab their lunch. Trying to get to class. We have to keep that six foot space. So we have to do two days a week," said Eden McCauslin, teacher at Taft High School.
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According to a recent CPS survey, only 44% of responding parents want their high schoolers to return to in-person learning.
Jackie Herigodt got her first dose of the vaccine Tuesday, and is now desperately trying to get one for her daughter Bella, who at 17-year-old will not be eligible to get one until the day she's set to return to Lincoln Park High School.
"It just doesn't make any sense to me, considering they're supposed to go back to school April 19 as a CPS student, and I'm not going to send her unless she's vaccinated," she said.
"My friends, I haven't been able to see at all. It sucks, a lot. But hopefully soon," said Bella Dunagan.
Mayor Lori Lightfoot said high schools will re-open as agreed upon by the district and teachers union several weeks ago.
"I see no basis for delay, and it's my expectation that we're going to be opening high schools as indicated by CPS," she said.
Even as negotiations over scheduling continue, CPS said they are already working on a plan to prioritize vaccines for students over the age of 16.