INDIANAPOLIS (AP) — Many teachers are choosing not to return to the classroom because of the coronavirus threat, and schools around the U.S. are scrambling to find replacements. In some places, that means lowering certification requirements to help get substitutes in the door. Several states have seen surges in educators filing for retirement or taking leaves of absence. The departures are straining staff in places that were dealing with shortages of teachers and substitutes even before the pandemic created an education crisis. Teachers in at least three states have died after bouts with the coronavirus since the dawn of the new school year.