Ginny,
This is an excellent ice breaker - I may have to try it. You have voiced a very common concern among many postsecondary online instructors. One approach is to provide all appropriate feedback, correction, recommendations, etc. for each deficiency, but just don't put the minus 2 or 5 or whatever next to every one of the deficiencies. Only subtract points for each type of error, not each error. I have used different colored pencils for each type of error, but it got a little cumbersome for me - but there are others who like it.
Thank you for your insights - maybe some of the other participants have additional approaches to share.
Dr. S. David Vaillancourt