Over at Teacher Magazine, they're in the midst of a pretty serious debate about whether or not test prep constitutes educational malpractice. The arguments probably aren't anything you haven't heard before. They argue that test prep limits the curriculum and removes the possibilities for innovative, student-centered curriculum. Again, this is hardly a groundbreaking argument.
First, it depends on whether you're teaching kids to succeed on the test or game the test. In all honesty, the test prep that I'm familiar with is a little of both. You cover the content and skills that are going to be tested (like how to identify a main idea), but you also teach little tricks about how to eliminate answers from a multiple choice format. Both of these lessons are useful on a test, but only one is useful when the test is done.
The real answer, of course, is that the value of teaching to the test depends entirely on the value of the test itself. If your end goal is an assessment that fully gauges student learning and achievement across a broad range of ideas and abilities, then by all means, teach to the test.
However, if you're looking at another field of endless bubble answers, gearing every element of your curriculum toward that product is probably not going to benefit your students much after they finish with the bubbles (if it even helps them there).
Assuming that test prep is here to stay (for at least as long as we have high stakes tests), we have to be extra vigilant about what kinds of tests we're giving. That's why it was so troubling to read (via Gotham Schools) that there's a proposal being floated to scrap the writing portion of next year's English test in New York. The reason, of course, has nothing to do with what's best for learning students, but rather what makes the test easier to grade. Seriously. I mean, it's bad enough that music, art, science, and history don't appear on the tests. But writing? Now that would constitute educational malpractice.