<p>I signed up but it didn't ask me to specify for E or M when I did. So how do I know which one I'm taking? Do I tell them there or something?</p>
<p>on test day, you get a booklet with ALL the subject tests in it. You get to pick, before you start, whether you want to do E or M. By picking I mean you have to bubble in the correct test that you are doing. That's all -- I'm sure you could bubble in the test information at the end, AFTER you've looked at both ;)</p>