Cricket2's post has me wanting to clarify a bit. While I don't regret using the extra practice test to get some basic "taking a test" experience, I would be very careful to avoid teaching the test material itself, especially if you're then going to use it to help make judgments about placement. It would be very easy to fall into the trap of just trying to maximize her score, but that is almost certainly not what you really want out of taking the test.