"Education must provide the opportunities for self-fulfillment; it can at best provide a rich and challenging environment for the individual to explore, in his own way. - Noam Chomsky
Education, in order to be rich and challenging, needs a solid foundation. This doesn't appear out of thin air; it is developed through hours and hours of research, reflections and preparation on the part of the instructor. A foundation supports the infrastructure. It's a collaboration of materials which creates a final product, not unlike the lessons that combine to teach a unit or the students who cooperate to arrive at a response. Good planning is the door to a good lesson (in my case, a messy desk is proof of time spent planning).
Bottom line- the objective of all lesson plans is to give students some skills that they can apply independently. If the lesson gives students opportunities to work in concert with their classmates, it replicates the real world work force. If the lesson succeeds in lighting the flame of curiosity inside the student, all the better.