I just proved you wrong, so please, don't use this as the one example where you were right and I was wrong. Schools can be rated on an national basis and states are rated, but not districts without some other parameter involved. I just told you the criteria (parameters) used in the three examples. On a side note, you really should check out how "an" and "a" are used in a sentence. Scroll down a bit.... <a href="http://owl.english.purdue.edu/owl/resource/540/01/" rel="nofollow" target="_blank">http://owl.english.purdue.edu/owl/resource/540/01/</a> Schools can be rated on <b>an</b> national basis.... You make this mistake in at least 20% of your posts.