MINNEAPOLIS (AP) — Minnesota schools are hurting from a substitute teacher shortage.

Teachers are heading to class sick and principals are splitting children between classrooms or even taking up teaching duties. The shortage is a problem nationwide as more substitutes are finding permanent work even as other teachers are leaving the field entirely.

The substitute teacher pool in Minneapolis is 516 this school year, down more than 60 from last year.

Some school districts have tried boosting pay for substitutes with little effect. Several education officials say it's a problem with the teaching pool as a whole.

Duluth teacher Bernadette Burnham says some teachers are being asked if they can make it through the day when they call in sick. She calls the shortage a crisis.