Write a Testable Hypothesis

3 - Construct a Hypothesis

A hypothesis is an educated guess about how things work. It is an attempt to answer your question with an explanation that can be tested. A good hypothesis allows you to then make a prediction: "If _____[I do this] _____, then _____[this]_____ will happen.”

Task #3B: Write a Testable Hypothesis

1. Read Writing a Hypothesis for Your Science Fair Project to learn more about why scientists write hypotheses and how to write a good, testable hypothesis
2. Answer the following questions to check your learning:
   1. Which of the following best describes a hypothesis?
      A random guess about the outcome of an experiment

      A detailed description of an experiment

      The best answer to a question based on what is known, which can be tested through experiments

      A summary of the results of an experiment
      Great job! A hypothesis is the best answer to a question based on what is known and must be testable through experiments.
      Nice try! Refer to the section on what a hypothesis is to understand its definition and purpose.
   2. True or False: A prediction based on a hypothesis should follow the format "If ____ then ____."
      True

      False
      Correct! Predictions often follow the "If ____ then ____" format to clearly state what will happen if the independent variable changes.
      Nice try! Refer to the section on writing predictions to understand the standard format.
   3. Which of the following is an example of a good hypothesis and prediction?
      Question: Do larger dogs eat more food than smaller dogs? Hypothesis: Dogs are friendly animals. Prediction: If dogs are given different types of food, they will eat it.

      Question: Does fertilizer help a plant grow bigger? Hypothesis: Adding fertilizer to the soil gives plants more nutrients and helps them grow. Prediction: If I fertilize some tomato seedlings, then those seedlings will grow taller and have more leaves than those not fertilized.

      Question: Does temperature affect the rate of a chemical reaction? Hypothesis: Temperature has no effect on chemical reactions. Prediction: If I increase the temperature, then the reaction rate will decrease.

      Question: Does light affect plant growth? Hypothesis: Plants need water to grow. Prediction: If I water the plants, they will grow faster.
      Correct! This example includes a clear hypothesis based on the question and a testable prediction involving an independent and dependent variable.
      Nice try! Review the examples of hypotheses and predictions to understand how to form a good hypothesis and prediction.

3. Fill out the form below with your project question, hypothesis, and prediction.

   NOTE: If you are using a Science Buddies project, be sure to read the entire project carefully before completing this step.

   • Project Question - If you don’t remember your question, look back at Ask a Question or Background Research.
   • Hypothesis - Based on what you learned in your Background Research, what is the most likely answer to your question?
   • Prediction - If your hypothesis is correct, what do you predict to see in your experiment? Be sure to write your prediction as ‘If _____, then _____’ and try to include both your independent and dependent variables in the prediction. 
   • Remember to document your question, hypothesis, and prediction in your lab notebook.
   Project Question:
   Hypothesis:
   Prediction: