When the teacher’s away, the students really do play.

A new study by Duke University Economist Charles Clotfelter says the image of spitballs flying past a daily substitute is often too real. The disturbing consequence is the amount of time students spend with substitutes—about a year from Kindergarten through high school—is all but lost in terms of learning. Clotfelter observed that, “Many times substitute teachers don’t have the plan in front of them… they don’t have all the behavioral expectations that the regular teachers have established, so it’s basically a holding pattern.”

Clotfelter examined North Carolina schools as part of emerging research that suggests that higher teacher absences lead to lower test scores. As schools find themselves under pressure to increase instructional time and meet student performance goals, the effect of teacher absenteeism has been all but ignored.

To be sure, teachers will get sick and should use their leave days to stay home and recover. But districts that pull teachers out of class for other reasons might want to reconsider: Teachers don’t have to be out for long for researchers to see performance losses.

Raegen Miller, a postdoctoral fellow at the University of Washington, examined the impact of teacher absences on 4th-grade test scores in a large, urban district he chose not to identify. His findings show that 10 teacher absences in a year cause a significant loss in math achievement. When teachers return after absences, additional time is lost as they re-teach material and restore order, Miller said.

Setting standards. The effect is more profound when substitutes fill in long term. Standards for substitutes vary widely but are far less than those required for regular teachers. Many districts don’t require subs to have college degrees or even to have attended college.

Long-term subs generally have better credentials than daily subs but are still a far cry from full-time teachers who’ve gone through the normal hiring process. Even the best long-term subs aren’t likely to meet the “highly qualified” standards of the federal No Child Left Behind Act (a bachelor’s degree in the subject being taught or passing a test to demonstrate subject-matter knowledge). To further complicate matters, the use of long-term subs to fill teaching vacancies is on the rise. Data from the U.S. Department of Education shows that the number of long-term subs used to fill regular teaching positions doubled between 1994 and 2004.

Making leave available. Nationwide, teachers are generally allowed 10 or more sick or personal days a year. Texas provides teachers with five days of personal leave each year and Texas districts typically provide an additional five days of personal or sick leave. Teachers may also be out of the classroom for professional development.

-“High Teacher Absences Hurting Learning,” by Nancy Zuckerbrod, Associated Press, Jan. 17, 2008.
-“Limiting use of subs can benefit students,” StarTribune.com, Feb. 10, 2008.