Becca,
I was thinking that one thing you could do to make this a little more interactive (perhaps for younger kids) is to have them draw a picture of a character in a scene. Then, another student could write the description based on the picture. When the descriptions are done, they could compare the original idea to the description from another person. It's similar to the telestration-type activity Wonhee and I did for the practice day. It might be best as a brainstorming activity.
Cheers,
Val