I just read Ben Joravsky's Bleader post on the ISAT debate in Chicago's public schools, and I want to add a point that is far from original but can't be emphasized enough.
Teachers didn't like the ISATs even when they mattered. They interfered with education. Teaching to the test isn't really teaching, and teachers were taught to teach to the ISATs as if nothing else in the whole school year was half as important. Now they're completely gratuitous.
CPS teachers know too much already about gratuitous. I knew a teacher who showed me the piles of boxes she kept in a corner of her classroom. They were the reports and forms she'd filled out in previous years because every autumn CPS had a bright new idea about how to track and quantify aptitude and progress, and by spring CPS had forgotten about it. So she kept the papers around in case someday somebody asked about them. She didn't expect that to happen.