Hi Barb:
I agree letting students know where they're weak in class is a good idea. I also think this gives the teacher an opportunity to connect with the student, to relate in a couteous, caring, and helpful manner. Sometimes students will share other information that indirectly reflects on their class performance. I think that's a great time to offer suggestions or advice and students usually appreciate teachers who demonstrate their helpfulness in contributing to the students success.
Regards, Barry