Try out Edmodo! It is touted as the Twitter of the Education world. I would say it is a very basic version of Blackboard. It has the ability to create a class and distribute the group id to your students. They log in without needing an email. Then they can chat with the entire group- not each other. The teacher can create a calendar and post assignments. You can also have students upload their assignments here. It then emails the teacher to let you know the student has submitted their work. It is a great tool. Try it out.
