In a transmedia presentation, students need to actively seek out content through a hunting and gathering process which leads them across multiple media platforms.
Kress argues that we need to teach students the affordances of different media through which we can communicate information and help them to foster the rhetorical skills they need to effectively convey what they want to say across those different platforms.
2010 Andrew Olle lecture from Alan Rusbridger - editor of the Guardian newspaper. "I am going to spend most of this talk tonight talking about what this digital revolution means."
He gives an excellent summary of the 15 things Twitter (as an example of social media) does effectively.