The ability to lean your boat and maintain upright posture is an essential skill for running whitewater.  We use the J Lean for ferries, peel outs, and hole surfing.  I find this skill easier on boats with edges than rounded boats.  You should be able to angle your boat 30° and paddle in a straight line for a distance - a drill I personally enjoy doing.  Here is a short video describing the J Lean and head placement: J Lean.

Putting on the brakes is an important safety skill.  Fortunately, this is quite easy in a kayak.  Basically, this is nothing more than the reverse stroke.  We will be asking you to get up to a decent speed.  Once you are fast enough, we will signal you to stop.  We want to make sure you stop reasonably quickly.  Here is a demonstration video: Stopping a Kayak.

The next drill we will practice is paddling the boat in a straight line.  Instructors will be separated roughly 50 yards apart and safety boaters will be interspersed along the way.  Groups of paddlers will paddle in a straight line in each direction.  We will be watching for good torso rotation, good paddle blade entry point, and recovery at your waist.  A good strong forward stroke is challenging to master but critical in whitewater.  We will also be watching closely to ensure no one has the dreaded "Death Grip".  We want clean forward strokes that use your torso.  Here is a nice article on forward stroke technique by a world champion: 14 Tips Forward Stroke (NOTE: This webpage takes a bit of time to load).