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1.2: Scientific Method

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    How many angels can dance on the head of a pin?

    This is a question that has been pondered over the centuries. Can it be answered using the scientific method? Is it a scientific question?

    The Goal of Science

    The goal of science is to answer questions about the natural world. Asking (and answering) questions is integral to the process of science. Scientific questions must be testable. Which of these two questions is a good scientific question and which is not?

    • What is the age of our planet Earth?
    • How many angels can dance on the head of a pin?

    The first is a good scientific question. It can be answered by age-dating rocks and by using other techniques. The second question cannot be answered using data. It is not a scientific question.

    Scientific Method

    Scientists use the scientific method to answer questions. The scientific method is a series of steps. These steps help scientists (or even just people!) investigate a question.

    Often, students learn that the scientific method goes from step to step to step in a specific order, like so:

    • Ask a question. The question can be based on one or more observations or on data from a previous experiment.
    • Do some background research.
    • Create a hypothesis. Use your imagination and reasoning skills.
    • Conduct experiments or make observations to test the hypothesis.
    • Gather the data.
    • Use logical reasoning to formulate a conclusion.

    In reality, however, the process doesn’t always go in a straight line. A scientist might ask a question and then start doing some background research. During his research, he may discover that his original question needed to be asked in a different way, or that an entirely different question should be asked. As a result, he is brought back to the first step of the scientific method.

    Ask a Question

    Now, let’s ask a scientific question. Remember that it must be testable.

    We learned in the previous concept, "Scientific Explanations and Interpretations," that the average global temperature has been on the rise. Scientists know that carbon dioxide is a greenhouse gas. Greenhouse gases trap heat in the atmosphere. This leads us to a question:

    Question: Is the amount of carbon dioxide in Earth’s atmosphere changing?

    This is a good scientific question because it is testable.

    Graph of atmospheric carbon dioxide at Mauna Loa Observatory

    According to data collected at the Mauna Loa Observatory in Hawaii, atmospheric carbon dioxide has been increasing since record keeping began in 1958. The small ups and downs of the red line are due to seasonal changes in the winter and summer. The black line traces the annual average.

    How has carbon dioxide in the atmosphere changed since 1958 (Figure above)? The line on the graph is going up so carbon dioxide has increased. About how much has it increased in parts per million?

    So we’ve answered the question. We used data from research that has already been done. Fortunately, scientists have been monitoring CO2 levels over the years. If they hadn't, we’d have to start these measurements now.

    Because this question can be answered with data, it is testable.


    • Scientific questions must be testable.
    • Scientists use the scientific method to answer questions about the natural world.


    1. What feature does a question need to have in order to be a good scientific question?
    2. Create a question that is a good scientific question. Create a question that is not a good scientific question.
    3. Look at the graph of atmospheric CO2 measured at the Mauna Loa Observatory over time (Figure above). How much has the atmospheric CO2 content risen since 1958?

    Explore More

    Use this resource to answer the questions that follow.

    1. What is the first rule of writing scientific questions?
    2. What is the second rule?
    3. What type of questions should NOT be used?
    4. What is the third rule?
    5. Write a good scientific question that follows the three rules.

    This page titled 1.2: Scientific Method is shared under a CK-12 license and was authored, remixed, and/or curated by CK-12 Foundation via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.

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