The Hypothesis: "Hypothesis" means "what do you expect to happen in your experiment?" Suppose your research question is, "what happens to seeds if I change the temperatures they are kept at before they are planted?"
The hypothesis might be "the higher the temperature that seeds are kept at, the quicker I expect them to sprout." It's important to word your hypothesis correctly. For example, don't say "higher temperatures are better for seeds." "Better" cannot be measured. Decide on a hypothesis that can be proved in a measurable way. For example, "higher temperatures will make the seeds sprout faster."
It is perfectly fine for your experiment to disprove your hypothesis. If something unexpected happens during your experiment, the project doesn't need to be trashed. You just discovered something new and showed that what we expect is not always what we get.
[From the Sci4Kids Science Projects Page]