I am working up a new media literacy unit for next semester. A colleague at SSU showed me a really fantastic Introduction to Media Literacy resource from the Media Literacy Project. What I like about the article is the clear delineation between beginning, intermediate and advanced literacy techniques. The 16 page document covers media literacy (in general terms) and then gives examples of different persuasion techniques media uses to influence viewers. There are concrete questions at the end of the document students can use to evaluate images and videos.
Once I develop a lesson plan, I will decide if I want students to evaluate a particular image, or if part of the unit will be them finding AND evaluating their own image from a normal daily activity (bus add, tv commercial, etc.). I highly recommend the resource.