How to Write a Hypothesis

Valorie Delp
science fair project

A hypothesis is basically your best guess as to what is going to happen during a science experiment. You should write it before your experiment, and it should be something you can test during your experiment. While it might seem daunting to come up with a hypothesis, there are some steps you can follow to ensure that your final statement is a good one.

Steps to Writing a Great Hypothesis

Whether you're working on a class project or a science fair, make sure you're putting your best foot forward with your hypothesis. The hypothesis is integral to the scientific method.

Ask a Great Question

The first step in getting a solid hypothesis is to make sure you're asking a good question for your science experiment. You know that you have a good question if you can find the answer to a question through an experiment. Examples of good questions might include:

  1. Who gets better grades on math tests: boys or girls?
  2. Which shape will make the strongest bridge?
  3. What song is most likely to become an earworm?

The questions above make great science projects because they are testable and through that testing, you can come up with an answer.

Start With a General Answer

At its base, a hypothesis is a general answer to the question you're posing in your science experiment. You can start by answering your basic question in a way that identifies the relationship between the two major variables. For example:
  1. Boys and girls receive different grades on math tests.
  2. The shape of a bridge affects how much load it is able to bear.
  3. Catchy songs become earworms that you cannot get out of your head.

Each of the statements above identifies the two major variables.

Refine With a Directional Statement

Once you have identified the relationship between the two variables, you'll want to refine your hypothesis by stating a direction of the relationship between the two variables. For example:

  1. Boys tend to get better grades on math tests.
  2. Bridges with construction that include a lot of triangle shapes are able to bear more weight.
  3. Songs with choruses that repeat at least ten times are more likely to become earworms.

Writing the Measureable Hypothesis

Finally, you'll want to write your hypothesis with the, 'If. . .then. . .because. . .' format. For example:

  1. If 8th grade boys take math tests that require spatial reasoning, then 8th grade boys will get, on average, higher grades than 8th grade girls, because 8th grade boys are better at spatial reasoning.
  2. If triangle shapes are used to create a bridge's tresses, then the bridge will be able to stand five times more weight than bridges with tresses that use other shapes (like arches or squares), because triangles are inherently stronger.
  3. If an upbeat song has a chorus that repeats at least ten times, a person is more likely to get the song stuck in their head, because it takes ten times of exposure for something to be cemented in memory.

Avoid Hypothesis Mistakes

To make sure you're putting your best food forward, avoid these hypothesis mistakes:

  • Not writing one - All experiments need to have a hypothesis. Sometimes students think that their experiment doesn't require one because they aren't asking a question. If that's the case, you need to come up with a question to answer.
  • Not answering the question posed by the experiment - If you are working on a more advanced science project, it's probably likely that before you can come up with a hypothesis, you'll need to do some research. Make sure that your research is contained in the abstract. Remember, the hypothesis only answers the question you're posing by your experiment. At most, it should only be a couple sentences long.
  • Being vague - Remember that your hypothesis should be formulated in such a way that it lets your audience know what you think will happen if you change one variable. In other words, 'If I do this. . .I think I will get this.'
  • Changing your hypothesis if it's wrong - Sometimes you do an experiment and discover that your hypothesis was completely wrong! If that happens to you, don't change your hypothesis. It's still a valid part of your experiment. Instead, your conclusion needs to indicate that your hypothesis was wrong and if possible, why it was wrong or what you'd do differently next time.

Part of the Scientific Method

Writing a hypothesis is an integral part of conducting a science experiment. In addition, it's frequently a judged part of a science fair project. In other words, you cannot get a good score for your science fair project if you don't have a hypothesis.

How to Write a Hypothesis