The terms prediction and hypothesis are often used interchangeably, yet one term means to think about what might happen and the other means to think about why something will happen. Misuse of these terms may deprive students of the opportunity to think critically. In this article, the authors attempt to demystify the terms prediction, hypothesis, theory, and law so that they can be used accurately and with confidence. They define each of these words in basic terms, and then explain each term using common examples.