If you're lucky enough to have a light table, here's a cool way to intrigue kids to write. Place a container of salt over the light table and allow students to write with a paintbrush or chop stick. You could put this activity at a variety of centers.
Descriptive Writing Prompt: PIck ONE monster. Begin a descriptive response: "Yesterday I found the most _______creature! I wish I would have had my camera with me, but I didn't. This creature. . . (describe the creature in detail) Read to partner, guess which creature was the focus.