One of the biggest issues in today's science classrooms is the problem of whether to teach evolution, creationism, or both. Creationism generally hasn't been taught because, like nearly all religion, it has reached its conclusion without using scientific methods. But now it's trying to enter our classrooms labeled as science -- under the name of "Intelligent Design."
Intelligent Design states that most life--especially humans--could not have come about through the process of evolution because it is too complex. However, the issue with this theory is that it doesn't follow the scientific method. Before I go on, let's clear up the meaning of a few terms:
Fact -- something that is directly supported by evidence. Example of a fact: Trees have leaves.
Hypothesis -- an explanation of evidence, a fact or phenomenon that can be verified and/or disproved. Example of a hypothesis: Trees have leaves to shelter themselves from the rain.
Theory -- A tested hypothesis that has been shown to be correct but can still be disproved. This is the highest rank an idea can achieve using the scientific method. Many people misuse this term to mean hypothesis (as in, "That's an interesting theory."). Example of a theory: Trees have leaves to collect sunlight, which they use for energy.
Opponents of evolution in schools have often cited the fact that the Theory of Evolution is just that -- a theory. This shows lack of understanding of science and terminology. Many of these same people support Intelligent Design, despite the fact that it's barely even a hypothesis. They also claim that evolution itself can't be proved or disproved. However, the fossil record could disprove evolution if there was enough evidence against it. Also, nearly all scientists agree that evolution has been proved on a cellular scale, though there's no consensus on macro-evolution's proof.
I'm not saying religion shouldn't be taught in public schools, but rather if it is, it doesn't belong in the science classroom.
Author's Note: Sources: http://www.fsteiger.com/theory.html, http://en.wikipedia.org/wiki/Scientific_method