A really fun and informative part of our class is the scenarios.  Some will be relatively simple like yard sales, others much more complex like foot entrapments and C-Spine rescues.  I often add subtle exercises as well ;-)  To add some reality, we will try some role playing like having some boaters pretend they are novices and bystanders.  As rescuers, you will need to be able to quickly determine which type of command structure fits the situation best and respond accordingly.