Another good online resource for school rankings and information is GreatSchools.net. Here's a link directly to the Clayton page. You'll see summaries of class size, ABC Designation (School of Distinction, School of Growth, etc), GreatSchools rating, and more. Click on each school for more information.
There are several schools in Clayton ranked "10", and very few with low scores.
Here's the link: http://www.greatschools.net/cgi-bin/cs_compare/nc/?level=e&area=m&zip=27520&miles=10&lat=35.636284&lon=-78.444817&sortby=distance&tab=over&begin=0