When students are able to construct their own vision within an assignment they become a part of it. I have seen some students who hate school (or at least they put that off as their defense mechanism) give me their absolute best effort in research and the carrying out of an experiment, when they have a say in parts of it. I will often allow the students to deviate from the norm of an experiment and let them roam free. This is when they truly get excited. Now I have planned for 90% of the possible directions that they can go, but there are some original ideas that come out if this that I have not heard. As long as the student can justify the reasoning of their venture, I am game.
Constructivism within the classroom is essential to a true measure of growth of an individual student. Not only can they develop a new appreciation for the content, but they learn life skills as well along the way. It is a higher level of cognitive ability as well as a higher level of maturity that we are teaching our students. They need to have the structure, but also need to perceive they have the freedom to incorporate their own ideas and ideology into the lesson. Only then will we get the greatest outcome.