Teaching the 8 & under kids to circle swim can be like herding cats, but there are dry-land drills you can use which will make you life easier. Did you know that sharks and stingrays sometimes hide along the center line? It is important for the little fish to stay by the lane line and swim around them.
For the adults who think that a pool lane is like an exercise bike and only one person can ride at a time, I have some advice as well. Be polite and learn how to share the lane with other swimmers. Circle swim is like driving on a two-lane road. When you follow the rules of the road and stay on your side, traffic flows easier.