A teacher I work with (and infrequent reader here...let's call him "Joe") has some very interesting things going on in his classroom. It energizes me to hear his ideas and discoveries...and makes me want to rattle the cages of other teachers.
Exhibit A: Living vs. Non-living things
Joe is providing a list of different things, some which might be more obviously associated with living (e.g. bacteria) and others which might be more difficult to discern (virus). The kids will think about the list, make a continuum of the items, and generate a basic definition of what it means for something to be alive. This definition will be revised throughout the year as kids move through different parts of the curriculum.
The other teachers are talking among themselves about how many qualities of life should be on the list. This book has six and that book has seven. What will we tell the kids? In other words, what will go on the overhead for kids to copy down and be tested upon? There can only be one answer.
Exhibit B: The Scientific Method
After an opening activity, Joe asked his kids to write about what it means to do science. Their paragraphs provided him with some eye-opening moments about the misconceptions that they have. This has allowed him to structure some further activities and conversations with students to help them correct their ideas and progress toward the standards. It also means that kids are learning to conceptualize parts of the scientific method (like controlled variables).
The other teachers are lecturing about the parts of the scientific method in the same way that kids were exposed to material in earlier grades and then doing a lab to see if the kids get it. If they don't, teachers will move on to the next point in the curriculum. Steps and vocabulary are to be memorized independent of experience.
Whether or not you cotton to the constructivist ideas for teaching, I still think that there's something to be said for letting kids do the work of learning. They need to be telling us what they know and we need to be generous enough to ask them about their learning...and quiet enough to hear the answers.