This week I was honored to speak at the Center for Teaching and Learning at the University of Oregon. I was asked to talk about evaluation, which is a big issue in the great northwest because of RtI (response to instruction). They are testing the heck out of kids towards ensuring that no one falls behind. It's a grand sentiment, but a poor practice.
Teachers there told me they were testing some kids weekly or biweekly. That is too much. How do I know it is too much?
The answer depends on two variables: the standard error of measurement of the test you are using and the student growth rate. The more certain of the scores (the lower the SEM that is), the more often you could profitably test... And the faster that students improve on the measure relative to the SEM of the test, the more often you can test.
On something like DIBELS, the standard errors are reasonably large compared to the actual student growth rate--thus, on that kind of measure it doesn't make sense to measure growth more than 2-3 times per year. Any more than that, and you won't find out anything about the child (just the test).
The example in my powerpoint below is based on the DIBELS oral reading fluency measure. For that test, kids read a couple of brief passages (1 minute each) and a score is obtained in words correct per minute. Kids in first and second grade make about 1 word improvement per week on that kind of measure.
However, studies reveal this test has a standard error of measurement of 4 to 18 words... that means, under the best circumstances, say the student scores 50 wcpm on the test, then we can be 68 percent certain that this score is someplace between 46 and 54 (under the best conditions when there is a small SEM). That means that it will be at least 4 weeks before we would be able to know whether the child was actually improving. Sooner than that, and any gains or losses that we see will likely be due to the standard error (the normal bouncing around of test scores).
And that is the best of circumstances. As kids grow older, their growth rates decline. Older kids usually improve 1 word every three or four weeks weeks on DIBELS. In those cases, you would not be able to discern anything new for several months. But remember, I'm giving this only 68 percent confidence, not 95 percent, and I am assuming that DIBELS has the smallest SEMs possible (not likely under normal school conditions). Two or three testings per year is all that will be useful under most circumstances.
More frequent testing might seem rigorous, but it is time wasting, misinformative, and simply cannot provide any useful information for monitoring kids learning. Let's not just look highly committed and ethical by testing frequently; let's be highly committed and ethical and avoid unnecessary and potentially damaging testing.
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