My school district is focusing on Written Expression--even in Reading Intervention. I had to come up with some way to assess (get some baseline data) on my students' written expression skills.
I decided to simply have my students write for five to ten minutes on a prompt. I've created five prompts for the first five days of school (I may develop some more as I see where I need to go with this). I also created a set of guidelines for the writing.
My plan for the first week is this: Give each student a printable with the prompt on one side and the guidelines on the back. *I may stop putting the guidelines on the back if I continue the daily writing. Set a timer and tell them to write. Then, I'll analyze the results and determine who I need to pull into Guided Practice to work on specific skills.
Anyway, I hope you find this helpful.