Why No TIMSS for Teachers?

U.S. students relatively poor performance on the TIMSS tests provided a large part of the political motivation to review Science, Technology, Engineering, and Mathematics (STEM) education. Despite media reports that claim the problems grow worse from 4th to 8th to 12th grades, a more careful analysis shows that the problems are equal across grade levels.

Given all the time and trouble it took to identify international participants, why weren't teachers tested too? Do those countries that bested the U.S. in student mastery of math also best the U.S. in teacher mastery of math? If our teachers are the equal of their international counterparts we can look elsewhere for the U.S. problems. But if the results are like this, we know what our first priority should be.