Good teaching matters ... a lot
By Kati Haycock
RESULTS - March 1999
Parents have always known that it matters a lot which teachers their children get. That's why those with the time and skills to do so work very hard to assure that, by hook or by crook, their children are assigned to the very best teachers. (That's also at least part of the reason why the children of less skilled parents are often left with the worst teachers.)Recent research from Tennessee, Texas, and Massachusetts proves that parents have been right all along.
"The difference between a good and a bad teacher can be a full level of achievement in a single year," says Eric Hanushek, a University of Rochester economist who most often suggests that virtually nothing seems to make a difference in student learning.
While these studies do not indicate how to create effective teachers, they do point to the link between effective teaching and student learning.
TennesseeTennessee is one of the few states with data systems that make it possible to tie teachers to achievement in their classrooms. Moreover, the state's value-added approach for assessing student achievement allows observers to look at the gain students make during a particular school year.
William L. Sanders, director of the Value-Added Research and Assessment Center at the University of Tennessee at Knoxville, has studied these data extensively. By grouping teachers by their effectiveness in producing student learning gains, his work allows us to examine the impact of teacher effectiveness on the learning of different types of students, from low to high achievers.
On average, the least effective teachers produce gains of about 14 percentile points among low achieving students; the most effective teachers posted gains that averaged 53 percentile points.
The Tennessee data show dramatic differences for middle- and high-achieving groups as well. For example, high-achieving students gain an average of only two points when taught by "least effective" teachers but an average of 25 points when taught by the "most effective" teachers. Middle achievers gain a mere 10 points with the "least effective" and in the mid-30s with the "most effective."
There is also considerable evidence that the effects of teachers are long-lived, whether they advance student achievement or squash it. Even two years later, the performance of 5th graders is still affected by the quality of their 3rd grade teachers.
Dallas
A variety of studies in Dallas show similar differences in achievement between students taught by teachers of differing quality. Borrowing from some of Sanders' techniques, researchers in the Dallas Independent School District recently completed their first-ever study of teacher effects on the ability of students to perform on assessments. In sharing their findings, Robert Mendro, the districts' executive director of institutional research, said "what surprised us most was the size of the effect."
For example, the average reading scores of a group of Dallas 4th graders who were assigned to three highly effective teachers in a row rose from the 59th percentile in 4th grade to the 76th percentile by the end of 6th grade. A fairly similar (but slightly higher achieving) group of students was assigned three consecutive ineffective teachers and fell from the 60th percentile in 4th grade to the 42nd percentile by the end of 6th grade. A gap of this magnitude‹more than 35 percentage points‹for students who started off roughly the same is hugely significant.
The impact of teacher effectiveness is also clear in mathematics. For example, a group of beginning 3rd graders in Dallas who averaged around the 55th percentile in math scored around the 76th percentile at the end of 5th grade after being assigned to three highly effective teachers in a row. By contrast, a slightly higher achieving group of 3rd graders‹averaging around the 57th percentile‹were consecutively taught by three of the least effective teachers. By the end of 5th grade, the second group's percentile ranking had fallen to 27th. This time, the youngsters who had scored nearly the same as beginning 3rd graders were separated by a full 50 percentile points just three years later.
BostonThe Boston Public Schools are looking seriously at factors that influence student learning, including teacher effectiveness. A study by Bain and Company shows the correlation between high school teachers and student academic growth in math and reading. The authors examined classrooms of Boston 10th graders whose average scores were about the same and charted their progress over the year by teacher. The differences were dramatic. In reading, they found that although the gains of students with the top third teachers were slightly below the national median for growth (5.6 on average compared to 8.0), students with teachers from the bottom third showed virtually no growth (0.3). The math results were even more striking. The top third teachers produced gains on average that exceeded the national median (14.6 to 11.0 nationally), whereas the bottom third again showed virtually no growth (-0.6).
Altogether, this means that the top one-third of BPS teachers are producing six times the learning seen in the bottom third. As one frustrated headmaster put it, "About one-third of my teachers should not be teaching."
SolutionsTeacher effectiveness is not forever fixed. Through careful development, teachers can build their effectiveness over time. Community School District #2 in New York City has invested generously in the professional development of principals and teachers. Teachers have received generous amounts of on-site coaching by expert teachers. As a result, student achievement has climbed steadily over the past 10 years. (Results, December/January 1999).
University of Michigan researcher David Cohen's recent study of professional development in California also shows the impact on student achievement when professional development focuses on new curricula and the content it undergirds (Results, April 1998.)
Similar results are evident in schools and districts that have been recognized by the U.S. Department of Education's Model Professional Development Award winners (JSD, Fall 1999). They have recognized that effective professional development strategies must be on-going, on-site, and focused on the content that students should learn.
Excerpted from "Good teaching matters: How well-qualified teachers can close the gap," by Kati Haycock, Thinking K-16, Summer 1998 and adapted with permission, Education Trust. A complete copy of this report can be downloaded from http://www.edtrust.org
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