A scientific hypothesis (pl. hypotheses) is an evidence-based, testable, and falsifiable (shown to be wrong) statement about how some aspect of the world works.
A simple example of a hypothesis could be "fire requires oxygen." It is evidence-based because fire is seen to exist in air, which contains oxygen, and can be put out by water which can cut off the air supply to the fire. It is testable because you can devise a test (removing oxygen from the area of a fire) that will either affirm the hypothesis or not. It is falsifiable because if you take away oxygen from a fire, and the fire continues to burn, the hypothesis is shown to be wrong.
- Make hypotheses as explicit, clear, and understandable to an outside reader as possible.
- Break complicated hypotheses down into sub-hypotheses.
- Each hypothesis should be able to be tested using a single test (or series of related tests).
- Hypotheses can be expressed as null and/or alternative hypotheses.
- Hypotheses can be written in sentences or paragraphs. They can also be numbered.