Why common assessments?

We are currently under pressure to create common assessments for ELA.  Often this makes more questions than answers arise:

• What kind of common assessment?  What should it look like?
• What are we assessing?
• When do we give the assessment?  How do we score it?
• What do we do with the results?

Common assessments are meant to be helpful.  They are meant to be formative in nature, and inform instruction.  But, more often than not, they end up being summative and punitive to the student.  A grade that is averaged into the report card that never truly moves a student forward.  So, the real question is:  How do we create a common assessment that will help move our students forward?