1. Intimacy in Communication
Some of our students are not aware that different means of communication involve a different level of intimacy. Obviously, speaking to someone eye-to-eye is more intimate than writing a mail or twittering something. If you want to make students aware of that and if you want to discuss this in class, here is a picture that illustrates the levels of intimacy in different means of communication.
2. Historical Development of Communication
If you want to tell your students something about how communication has developed over the time, here is a nice illustration of all the important steps from 30,000 before Christ to today.