One of my classes just took an exam and exhibited bimodal performance. Half of the kids did very well and did not miss any conceptual understanding, only a very few (1 or 2) arithmetic errors throughout the entire exam. The other half of the class is missing large chunks of the conceptual setting-up-of-equations and making-predictions type of work. The split is about even.
So, what to do now? My intuition is to complete a concept map/graphic organizer as a class and then set them up in expert-novice pairs to work on remediation, and then the kids who need the extra practice are going to go home with a fresh sheet of problems and be asked to work through it to get additional reinforcement.
What would you do?
PS. I think one of my mistakes was to wait too long to have a large assessment. That's obviously easy to fix in the future, but I'm curious what you think I should do now, given the current situation.