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Based on your observations, a question can be formed. Keep in mind that not every question is a “good” question to test with the scientific method. In a lab, you should focus on testable questions, or questions that can be answered by doing an experiment. They are not opinion questions or questions that can be answered by doing research in a book or on the Internet. For example, "Is cake the most delicious desert?" would not be a testable question, because it is based on opinion.

Developing a good question is important because it gives your experiment direction and informs others of what you are trying to do in your experiment. It must be clear. A question such as “How do females learn best?” is not clear because there are many different ways to test it. A better question might be “Do females learn better when they study before or after they sleep?” because it only tests one condition (studying before or after sleep). Keep in mind that you must measure the results in some way for it to be considered a testable question.

Identifying the Variables

Once a scientist has a question, they then form a hypothesis, or an educated guess as to what will happen. First, however, they must determine the experimental variables. Variables are conditions that could affect the outcome of an experiment. Think about all of the different things that might affect how well a student performs on a test (for example, the amount of sleep they get, how long they studied, how well they paid attention in class, if they are feeling well). All of these variables and more could affect how well they perform.

Successful experiments include as few variables as possible. However, you will always have three types of variables: independent variables, dependent variables, and controlled variables.

The independent variable is what you change in an experiment. In contrast, the dependent variable is what you measure in an experiment (the results). The controlled variable accounts for the condition(s) that must remain constant during an experiment. Experiments require controlled variables so that you can determine if the independent variable actually causes the result. In a perfect world, all of the variables would be controlled except for the independent and dependent variables. This can be difficult to achieve, but is a very important goal.

Hypothesis

A hypothesis is a type of statement that predicts how changing one part of an experiment will affect the results. It is not a guess. It is an informed and well-thought out prediction based upon your background research. Many times, a hypothesis is best written in the “If______, then_________” format. The blank space after the “if” describes the independent variable and the blank space after the “then” describes the dependent variable. For example, “If females study before sleeping rather than after sleeping, then they will perform better on their exam the next day.”