Once the kids get a look at the boat being uncovered at the dock, they'll be all over it like sugar ants. Stowing the gear is a great way to keep them in one place while you get yourself situated. It will also give them a greater understanding of supply versus space. (So that's why we can't all bring four pairs of shoes.) Teaching this skill will pay dividends in time management for you after a few excursions.
OK, maybe there's a more-dignified job title for this, but what kid doesn't like to control the water hose for rinsing the boat? Even more fun for younger children, suggests Keith Ammons: Present the hoser with his or her very own super soaker/water cannon to do the job. With that in hand, who wouldn't want to be a hoser?
As you head in and approach the dock, one child prepares a bow line, another a stern line. With all crew members on the boat, each specialist sets up the looped end on the boat cleats and holds the lines with both hands until the vessel is where you want it at the dock. Make sure they don't stand up or reach over the gunwale until you say it's safe to do so; this will keep them from moving around the boat during docking and teach them the basics of using docklines.