EXPLAINER: Why are Chicago schools, teachers union fighting?

CHICAGO (AP) — Chicago scrapped classes for five days days in a confusing standoff that ended late Monday with the teachers' union over COVID-19 safety measures in the nation's third-largest school district.

From remote instruction to testing, both sides have been negotiating nearly a dozen complex points of a safety plan that loomed over students' return from winter break. The fight came as other districts have had to increasingly shift online amid soaring COVID-19 cases.

Leaders on both sides described the tentative agreement, which requires a full union vote, in general terms, but did not offer specific details.

Here is a closer look:

REMOTE LEARNING

The issue that caused the most chaos in the roughly 350,000-student district was when and how to revert to remote learning.

The Chicago Teachers Union wanted the ability to switch to districtwide remote instruction and offered a lower bar for closing individual schools. Initially, they proposed metrics similar to last year's safety agreement, which expired before the school year and remained under negotiation.

School leaders flat out opposed any districtwide return online, so much that they opted to cancel classes rather than allow it temporarily as the union argued was necessary amid the spike. Chicago Public Schools leaders said the pandemic is different now compared to a year ago with availability of vaccines and roughly 91% of staff vaccinated. School officials also said remote learning is detrimental to students.

Two days after students returned from winter break, the union voted to return to remote instruction on its own and most union members stayed out of schools, saying they would return when there's a deal or the latest surge of infections subsided. The district responded by locking them out of teaching...