New science test scores on the National Assessment of Educational Progress were released today, and they’re not comparable to the scores for earlier years. You may want to know whether our schools are getting better or worse over time in this subject, but apparently the federal government is more ambivalent.

There are actually two different flavors of the NAEP tests: the Long Term Trends (which stay the same over time so that we can see, well, trends), and the “Nation’s Report Card,” which can be redesigned whenever it is absolutely… convenient.

But here’s the thing: the NAEP Long Term Trends science test has not been administered since 1999, when it showed that a statistically significant decline in achievement had taken place at the end of high school since the test began in 1974 (see the chart below). If there’s an official reason for its discontinuation, I’m not aware of it.

The “Nation’s Report Card” science test that was administered in 1996, 2000, and 2005 also showed a statistically significant decline over that period at the end of high school. Today America learns that that test has been discontinued, too. The new “Report Card” science test is not comparable to the earlier one, so now we have no national measure of science trends at all.

Maybe there’s an excellent reason why the federal government no longer wants to measure trends in science achievement, but if there is, I suspect it’s political rather than educational.