Check out this site for funny ways to teach grammar and punctuation.
A review of the basics is always beneficial. This poster, created by the folks at www.knowledgeunlimited.com, measures 18- by 25-inches. You can order it for just under 15 dollars at http://www.thekustore.com/kucatalog.cgi/7124P
This lists the rules for comma usage. This addresses the Common Core standard for 6th Grade Language: 6.SL.2. Demonstrate command of the conventions of standard English capitalization, punctuation, and spelling when writing.