This month's issue of Scientific American has the front-page: A Crisis In Physics? with a featured article by Joseph Lykken and Maria Spiropulu titled Supersymmetry and the Crisis in Physics. Reading the article reminds us that science is continuously advancing and new ideas are always replacing old ones, even in the case that the old ones are not that old at all! This situation is one to take into account when teaching science. One has to be able to transmit to the learner that ideas, methods, and processes in general can be improved and that even basic knowledge (things thought to be true in the absolute) are in fact ideas that can be improved and in some cases replaced by better models of reality.
The fact that we have now so many of these hypothesis that have been proven to exhaustion and that are the subject of most content in science education makes it difficult to instigate in the student a sense of healthy skepticism. It is almost impossible to provoke the need for inquiry of things that the teacher is showing as tried and true and based on solid evidence without falling off the cliff of complete ignorance and denial. One doesn't want to teach that the theories of gravitation, evolution, electromagnetism, plate tectonics, etc. are false, but that they have many details unanswered and more research has to be done. Some of these "details" can be huge concepts of deep intrinsic interpretation that could at a point change the way we understand the reality of our world. No better example than "String Theory" that is trying to explain what is that we are made of.
My question now is how can I teach basic "principles" that have been proven to work so far and at the same time create a safe environment for my students to ask anything?