I will always remember when my mom taught my classes and when it got too loud she would have us all get on our knees and someone would say a prayer. I was always so embarassed as a young child, but it worked.
Also, in Teaching, No Greater Call http://www.lds.org/pa/display/0,17884,6003-1,00.html
In the first paragraph of Part B it suggests to select a disruptive classmember and show them in five ways that you care about them and she if their misbehavior changes. Try this one other classmembers also.
Hopefully it gets better :D