With all the earlier caveats, let’s start with the statewide distributions of teachers’ average SGP scores in reading and math.
Brian Davison points out that both distributions are reasonably symmetrical, suggesting that we do not have an unusually large number of teachers doing particularly well or poorly. That said, no parent will want a child to be subjected to the reading teacher in the first percentile, the other teacher in the second, or the three in the eighth.
The math scores are more widely distributed, showing a larger number of excellent and a larger number of awful teachers.
Aside from targeting the lowest performers in both subjects, these data suggest that we need math retraining more than reading.
Turning to the data by grade, here is the distribution of fifth grade reading averages.
The orange curve is a normal distribution, showing the least squares fit. The average and standard deviation of the fitted curve are shown at the base of the graph.
The distribution of sixth grade reading teachers is close to the same.
We already have seen that the Richmond average reading SGP plunges from fifth to sixth grades.
The Richmond distributions conform to that pattern. First, grade 5:
(Note that this average by teacher is slightly less than the average by student, above.)
As you see, this distribution is a bit wider than the statewide distribution. That is, Richmond has relatively more excellent fifth grade reading teachers than the statewide average, and also relatively more who are not performing. Five (of sixty-seven) Richmond teachers are more than two standard deviations above the state average; three are more than two standard deviations below.
Those teachers at the low end need some work but, for the most part, Richmond’s fifth graders are in pretty good hands as to reading.
Then we have grade 6 reading results:
Only one of Richmond’s twenty-one sixth grade reading teachers produced an average student improvement better than the state average; none was more than two standard deviations above the statewide average. Six (or seven, depending on the rounding) were more than two standard deviations below the state average and four were more than three standard deviations below. The Richmond average is 1.5 standard deviations below the state average.
These data tell us that Richmond’s sixth grade reading teachers are not doing a bad job. They are doing an appalling job.
Upon some reflection, the data also tell us two even more important things:
- The principals (and the Superintendent) now have a quantitative measure of teacher performance (at least as to reading and math). If they don’t do something (soon!) about rewarding the excellent performers and retraining or firing the poor ones, we’ll know they need to be replaced themselves.
- VDOE is hiding the identities of these high- and low-performing teachers from the parents who pay them and the teachers and whose kids are directly affected by teacher performance. Apparently those bureaucrats think it would be intrusive for the parents of Virginia’s schoolchildren to know whether their kids are in the hands or excellent, average, or lousy teachers. I think the term for that kind of inexcusable bureaucratic arrogance is “malfeasance.”
Tomorrow, the Math situation. (Hint: It’s even worse.)