Why do we science teachers teach theories in science?
"Facts and evidence" are important for one to know so that students have some practical knowledge about the world. But the meaning of "facts and evidence" is what allows students to predict "what will happen if...?" and how to make and use technology to get the job done. Theories are the framework that give the "facts and evidence" meaning so that predictions can be made more accurately and so that technology that works can be produced.
In modern science, students are expected to learn both facts and theories for a more complete understanding of what we currently know about the universe--especially our world; and to more effectively predict what will happen in our world and be caused by our interactions with it.
Man has come a long way since nature's response to man's activities was considered magic or curse or blessing. It is the theories of science, even the ones that have been replaced with better theories, that have brought us to our current state of understanding of "cause and effect" in all realms of science and human endeavor and to our current state of technological achievement.
Think about the power of the Germ Theory in curing disease. Think about the Theory of Relativity in space travel and faster cars; the Electromagnetic Theory of light in developing lasers; the Atomic Theory is making plastics and MEMS and computers; and, yes, the "Theory of Evolution" in establishing principles of ecology and sustainability and in designing programs that will allow man to maintain society/civilization in response to the changes in the biosphere that are coming as the result of global warming.
I say teaching theories is a good thing.
I just read a blog post and its comments. That inspired me to comment back. The above is what I had to say about presenting scientific theories in the science classroom (k-12). Another reader had commented that today "facts and evidence" were being replaced by theories in the science classroom, or something to that effect. So here I am on my soapbox again.