Which has a more profound effect on student achievement
— teacher and school quality or student background?
Quantitative research conducted over the past
35 years provides an answer to this question.
A McREL meta-analysis of research on the school
and teacher impacts on student achievement found that school-level
and teacher-level factors account for 20 percent
of the variance in student achievement. Student characteristics
—home environment, learned intelligence / background knowledge,
and motivation — account for 80 percent of
the variance in student achievement, as shown in the graphic below.
At first blush, these findings might appear to
suggest that school and classroom improvement have at best, a marginal
impact on student achievement. However, quite the opposite is true.
To illustrate this point, suppose that we could
evaluate and rank order all of the nation’s 92,000 public
schools according to their effectiveness — that is, variables
they control, such as instruction, curriculum, and parent involvement
(see school
improvement for a complete list of these variables).
Next, let’s consider schools to the far
right of the distribution curve — that is, schools ranked
at the 99th percentile in terms of their effectiveness. In these
schools, we would expect to find 84.7% of students passing a test
on which the normal pass rate is 50%. This would be true for any
school in this group, regardless of the background of students who
attend the school.
