I've now had three 90 minute classes using a set of iPads for group work. With the mix of discussion and group work I find myself using 3-4 sets of problems per class. Each group is assigned one problem per set for which to post a solution to Moodle and then encouraged to work the others while waiting for other groups, etc. How does this compare to those of you using physical huddle boards or clickers for active learning in class?