Parents:
Amazon has published their lists of best books of 2012. Here are their picks for Middle Grade and Teens. Please note that some of the teen books may more appropriate for high school students than for seventh grade students because of "mature content and themes."
Middle Grade:
http://www.amazon.com/gp/b/ref=pe_253370_27189050_pe_b3/?node=5917240011
Teen:
http://www.amazon.com/gp/b/ref=pe_253370_27189050_pe_b4/?node=5917241011