Every science experiment has some components that are required for an experiment to be considered valid, whether that experiment is conducted by an expert or a student who is working on a science fair project. Every experiment must have a hypothesis, which is declared before the start of an experiment. An experimental writeup must also have a conclusion. Every valid experiment must have a hypothesis and a conclusion, without exception.

Scientific Method

The scientific method is the method which all scientists use to observe the world around us. We are naturally biased, and the purpose of using the scientific method is to try to be as unbiased and objective as possible when testing ideas. The scientific method has four basic components: observing a phenomena of the world, creating a hypothesis to explain the phenomena you see, using the hypothesis to explain other, related phenomena, then testing to see whether the hypothesis is correct.


The scientific method revolves around the hypothesis, which makes the construction of the hypothesis one of the most important parts of planning an experiment. The point of a hypothesis is to focus an experimental procedure to answer a single, specific question that will create a conclusive answer. A hypothesis demonstrates an observation that you have made or a theory that you have about the world and is typically presented as a statement rather than a question.

Constructing a Hypothesis

To make a hypothesis, first conduct research on the subject that you are testing. This will give you information to base your idea on to make a more informed guess about the outcome of your experiment. Your hypothesis, then, is a prediction about the outcome of the experiment. For instance, after researching LED grow lights, you might determine that "plants grown under LED lights will be bigger than those grown under traditional grow lamps." This is a statement based on research and observations that can be tested conclusively. A hypothesis that cannot be conclusively tested is not valid. At the end of the experiment, you must be able to say whether the hypothesis was true or not.


A conclusion states whether the hypothesis was true or not and what evidence from your experiment supports your conclusion about the hypothesis. Your conclusions should also summarize the information gathered from the experiment, state your observations of the variables, discuss what flaws there might have been in the experiment and what further experiments could be done. Remember, a hypothesis that is proven false is not an indication of a failed experiment, as the information gathered from the experiment is still valuable.