Friday, June 08, 2012

Teachers Matter

Diane Ravitch is confused by something that Melinda Gates recently said about the potential of teachers:
When Melinda Gates was interviewed on the PBS Newshour on June 4, she said something that surprised me. I will give you the full quote, which I copied from the Newshour website. I was surprised because I never heard that claim, I don’t know whose research she was citing or if it even exists. I checked with Linda Darling-Hammond, who seems to have read every study of teacher effectiveness, and asked her if she knew the source; she said she had never heard this claim and had no idea where Melinda Gates got this information, if it exists.
So, I ask my readers, and I ask you to ask your friends in the academic world, do you have a citation for this statement?

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.
This was fairly easy to find, as I'd read it before.  Melinda Gates is referring to a 2011 Eric Hanushek article, which said, "The magnitude of the differences is truly large, with some teachers producing 1.5 years of gain in achievement in an academic year while others with equivalent students produce only 1/2 year of gain."

The original source for the finding is Eric Hanushek, "The Trade-off between Child Quantity and Quality," Journal of Political Economy 100 no. 1 (1992): 84-117 (at p. 107). The article can be downloaded here. His dataset was from the Gary Income Maintenance Experiment, which took place between 1971 and 1975, and which involved exclusively low-income black children.

So it's not the most recent or externally valid finding one could wish for, that's certainly true. 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.

And an even bigger question would be whether we could design an educational system (other than homeschooling or private tutoring) that didn't force kids into the straitjacket of a single grade every year, but was instead so tailored to their individual needs that they could move 1.5 or more years ahead in one subject even if they were on or behind grade level in another subject.



Blogger Education Realist said...

Wow, that was an interesting skip.

Gates said "We know from good research...."

You acknowledge that, perhaps, we know no such thing because the research is old and has a very small sample size, but really, what does that matter? What's really important is that it seems reasonable, doesn't it? So we should keep skating right by whether or not we know it, since we don't, and go instead to finding and categorizing these teachers. These teachers who have results that we aren't even really sure exist.

4:20 PM  

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