A scientific theory is a well-substantiated explanation of some aspect of the natural world, based on a body of knowledge that has been repeatedly confirmed through observation and experiment.
"... Theories generally provide mechanisms that explain the things we observe. There is a theory known as the kinetic theory of gases that provides a mechanism for understanding Boyle’s law. In the kinetic theory of gases, we make various assumptions about how the molecules in a gas act. In the most basic form, we assume that gas molecules run into one another without sticking and that they move about randomly. We assume that the molecules have an average kinetic energy based on the temperature. Those basicassumptions lead to Boyle’s law holding true. Because the kinetic theory of gases provides a mechanism rather than just a description of results, it qualifies as a theory. The kinetic theory of gases will never become a law, because that’s not what theories become. If a theory is any good, it explains a law. The kinetic theory of gases explains Boyle’s law, but the theory does not evolve into the law. The highest award for a theory is that it is a good theory, not that it becomes a law...."
One reason I learned a lot when I was first teaching Chemistry was that the explanation I had to give in class was in fact what Chemistry was all about. Theories are the explanations provided by scientists so that we could better understand the world we live in. Theories are the concepts, the substance of science. Teaching science means teaching its theories. The atomic theory of matter is how a chemist explains some of the things we observe like color, taste, odor, softness or hardness.
It is therefore baffling to hear someone say that when teaching science one must find different ways of explaining. Does that mean offering different theories? That, of course, is not possible. Only good theories should be taught although one can possibly present a bad theory to illustrate an example when a theory must be discarded. The theories are the explanations. So perhaps, it means to try and present the same explanation with different styles (like slowly and not too fast; or with slides not with chalk). Nonetheless, what is important here is to realize that since the main substance of science is its theories, and theories are the concepts, teaching science is indeed so much more than just teaching skills, it is teaching explanations.