The problem: there aren't always enough substitute teachers to cover those classrooms. This is part of a larger, teacher shortage across Illinois.
So what's behind the shortage, what districts are most impacted and what's being done to make sure there are teachers in every classroom?
Discussing all that is Jeff Vose, president of the Illinois Association of Regional Superintendents of Schools. The association conducted the survey on absences and another on teacher shortages.
For more information, visit iarss.org.