Today's Friday, which means there's a pretty good chance your child is being taught by a substitute teacher. According to this new study by the Center for American Progress, public school teachers are more likely to be absent on Mondays and Fridays, and on any given day one in 20 teachers is out. Their absences add up to $4 billion a year in substitute teacher payments and associated administrative costs. USA Today's Greg Toppo reports that study author Raegan Miller suggests paying teachers for unused sick leave. Read more of the study here and read Greg's report here.