Bad Teachers Put Students At Big Disadvantage, Study Finds
If students get a bad teacher in third grade, their test scores will still be suffering two years later, according to a new University of Tennessee study.
And students who get three bad teachers in a row are at a huge disadvantage to students who get three average or highly effective teachers.
"It basically says that school administrators should pay special attention in assigning students to teachers," said Dr. Williams Sanders, the University of Tennessee statistician who conducted the study.
"And if students are assigned to a relatively ineffective teacher, then for goodness sake make sure they have an effective teacher the year before and the year after." Sanders said the study is a preliminary report that will be followed by more thorough research.
The study is based on teacher effectiveness scores generated by "value-added assessment," the statistical system designed by Sanders to measure student achievement statewide. Value-added assessment measures how much students improve from year to year on Tennessee Comprehensive Assessment Program (TCAP) tests.
The tests are given to students in grades 2-8 in five subjects - math, reading, language arts, science and social studies.
The teacher effectiveness scores are based on how much each teacher's students improve.
Sanders' study shows students of all ability levels suffer when they get a relatively ineffective teacher and make big gains with a highly effective teacher.
The study examined TCAP math scores of fifth-graders in two metropolitan Tennessee school systems, identified only as System A and System B. Students who had ineffective teachers in third, fourth and fifth grades had average math scores in the 44th national percentile in System A and the 29th national percentile in System B.
Students who had highly effective teachers all three years had average scores in the 96th percentile in System A and the 83rd percentile in System B.
"The range of approximately 50 percentile points in student mathematics achievement as measured in this study is awesome," the report says. "Differences of this magnitude could determine future assignments of (students to) remedial versus accelerated courses."
Students who had three straight years of average teachers scored between the high and low groups, with average scores at the 80th percentile in System A and the 50th percentile in System B.
And students with a mixture of effective teachers - two ineffective followed by one highly effective, for example - also had mixed results.
Sanders said that means one highly effective teacher can't completely offset a previous ineffective teacher.
"If I'm a kid who has a low teacher and then I have two really high teachers, then my gains will tend to be very high under those (high) teachers, but I don't on average get it all back," he said.
Although the study deals only with math scores, Sanders said other subject areas show the same trends, although less dramatically.
The study also found race had no impact on student value-added performance. Black and white students were equally affected by effective and ineffective teachers.
Dr. Sam Bratton, coordinator of research and evaluation for Knox County, Tenn., schools, said elementary school students are currently assigned to teachers randomly, a practice that may be affected by Sanders' findings.
Calling Sanders' study "very powerful information," Bratton said, "It needs to be broadened and expanded and turned all different ways. This is just the tip of the iceberg."
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