Last week, Diane Ravitch called for a cite on a frequently used factoid from the Big Book of Eduformers: research shows that students with effective teachers make three times the progress of students with ineffective teachers.
More than a few commenters found the cite: Eric Hanushek, “The Trade-off between Child Quantity and Quality,” Journal of Political Economy 100 no. 1 (1992): 84-117 (at p. 107).
The research conclusions are based on the data from the Gary Income Maintenance Experiment, which took place between 1971 and 1975, and which involved 1920 exclusively low-income black children.
Just to show how rarely anyone has read the original article, check out these quotes: “There is… no evidence that changing the immediate circumstances of the family will have any effect on student performance. The work behavior of the mother has no influence on the educational performance of the children. Neither does the absence of a father.” (page 113) and “Of the determinants of teacher expenditures per pupil (ie, teacher experience and degree level and class size), only years of experience are significantly related to student performance. (page 109) (emphasis mine, in both cases).
I suspect the emergence of the actual article will result in Ravitch and others calling bullshit on this cite in the weeks and months to come, and the eduformers will be backing off, for reasons that eduformer Stuart Buck make clear:
“So it’s not the most recent or externally valid finding one could wish for, that’s certainly true.”
Then comes the amusing part of Buck’s post, and the reason for mine:
“But is it so implausible that some teachers could produce 1.5 years of learning while others produce half a year? The real questions would be how many teachers are in each category and how we can identify them accurately, without crediting or blaming them for outside-school factors.”
Melinda Gates: Well, we know from good research that the fundamental thing that makes a difference in the classroom is an effective teacher. An effective teacher in front of a student, that student will make three times the gains in a school year that another student will make.
Suppose Gates had said “Well, I believe that effective teachers are fundamental. Is it so implausible that some teachers can produce three times the gains”? Doesn’t have nearly the ring of authority, does it?
So we’ve seen the research. It’s old, it’s demographically limited and the support is pretty weak to boot.
But hey, it’s pretty plausible, right?
Factoids are so much fun. Until, you know, someone actually thinks about them and the romance goes poof.