Most high school students will take a course in biology to learn about cell structure, genetics, and evolution. It stands to reason that those students will have a teacher who is an expert in the field -- a teacher who majored in biology or passed a test to demonstrate content knowledge mastery. Yet, many states do not require that level of expertise.
When we evaluated high school content preparation in the Teacher Prep Review, we were alarmed by the seemingly random nature of certifications across the states. A certification may not require a licensure test, a state may offer only a single certification for all of the sciences, or a certification may be single-subject by name, but allow for teaching assignments in unrelated subjects.
Here are three states' certification pathways for becoming a biology teacher:
Colorado offers only a general science certification that allows anyone with any major in the sciences to teach any science course without even having to pass a licensure test. You can literally major in physics and teach biology.
North Carolina offers a certification in biology, but requires no licensure test to validate content knowledge. Moreover, North Carolina offers a (general) science certification for which a candidate completes a sort of science mash-up major and for which there is no licensure test. So, again, a biology teacher may only have a smattering of biology knowledge.
Of these states, Tennessee is the only one that limits high school biology instruction to a teacher who majored in biology and passed a test to demonstrate content knowledge -- a model design that helps ensure a knowledgeable teacher is in every classroom.
So, where is biology not biology? It all depends on the state you teach in.