How to Write a Good Hypothesis

An “If… then…because” statement in a hypothesis tells the readers what you believe will happen in an investigation when something is changed, so you can see the effect of the change.

• IF…tells the readers what will be changed.  This is the manipulated (independent) variable in the investigation. 
• THEN… tells the reader what will happen because of the change (manipulated variable) described in the If… statement.  This is the responding (dependent) variable in the investigation.
• BECAUSE… tells the reader how you know this will occur.  It should be based on something you have experienced, or perhaps something you infer.
• Whenever an experiment is done, controlled variables are factors that do not change between all of the experimental groups.

Examples

• If 7^th graders and 8^th graders complete the same math problems, then the 8^th graders will have more answers correct, because they have studied math for one year longer than the 7^th graders.
• If dry bread and moist bread are left in bags for two weeks, then the moist bread will grow mold more quickly than the dry bread, because mold is a living organism, and organisms need water to survive.
• If some students eat breakfast before school and others do not, then the ones who do eat breakfast will have better grades in their morning classes, because their brains have more energy to think.