I came across this wonderful tutorial demonstrating how to use the social networking site for educators called Edmodo.  I have been using Edmodo with the fifth graders for a few weeks now.  The students love to communicate with one another.  We have also completed polls and are learning how to use the assignment feature.  After watching the video, I began to realize just how powerful this social networking site could be.  Check out the video and you may find Edmodo useful for your class.