Gains achieved by students who exceeded the previous year: PPS compared to ACCESS
It is well established that high-achieving students make lower gains than other students. This has been found in districts across the country and it is also true for Portland Public Schools, where students who exceed benchmarks consistently make lower gains than other students. See the results for 08-09 here. I have often heard that this was a result of students hitting the "ceiling" on the tests and did not reflect the student's learning or instruction.
Under a very silly provision of No Child Left Behind, state tests must measure students against grade level expectations, not against higher expectations. This does put a lid on how much students can demonstrate that they know when they have been working above grade level, but the Oregon OAKS, as a computer-adaptive test, has a somewhat higher "ceiling" than paper and pencil tests.
I was curious to see whether the testing ceiling was in fact making it impossible for high-achieving students to make gains, so I compared the gains made by ACCESS students with those of other students in Portland who "exceeded" benchmarks. ACCESS admits students in the top 1% of achievement--if there was a ceiling they should be hitting it harder than other students. They might have higher scores to begin with, but they would not have higher gains. If, on the other hand, the difference is a reflection of real differences in instruction, then ACCESS students might continue to outperform other students in PPS who also exceeded benchmarks.
PPS only recently began posting ACCESS scores separately from those of the other students in its shared building.
The results are below. I have included the mean achievement levels of the same group of students from the previous spring, so it is evident that ACCESS students are beginning the school year with scores about 3 points higher than their classmates in other schools who also exceeded benchmarks. If they followed the normal pattern, the higher their starting score, the lower their gains would be. However, this was not the case. ACCESS students continued to make higher gains than their classmates, in both reading and math with the exception of a loss in fifth grade reading that was two-tenths of a point worse than PPS.
This spread reflects the gains that other "exceeds" students could be making in PPS if they had access to appropriate curriculum and instruction. It is a learning opportunity that has been taken from them. In fact, it is a very minimal estimate because, as noted above, the tests that are being used don't truly measure what these students know. Out-of-level testing for all students who exceeded would reveal a greater spread and would also significantly reduce the margin of error on the tests.
2009/10 gains, PPS and Access (the test score means from
the previous year are included)