1) You can talk about audience. Creating a poster has a lot to do with
catching attention of a certain group of people. Can the children get
into groups and think: What type of posters do I like? What kind do my
older cousins like? My parents? Who do I want to look at my poster?
2) Text. Show examples of one sentence written in a variety of ways,
(caps, small, large, script, print) what type of message/emotion comes
across when they see these different words. Do they want one word? A
sentence? Or maybe just a symbol?
3) Try scanning in things (if possible) pictures objects, drawings.
You said you were doing places in virginia? It could be tickets, maps,
postcards etc.
4) You could talk about the relationship of color to the subject
matter. Do I want to use pastels? If I do what does this mean for my
topic?
5) How can I tell a story? Here is a good example from a UNICEF competition.