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1.2: Scientific Method

Difficulty Level: Basic Created by: CK-12
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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 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!) to investigate a question.

Often, students learn that the scientific method goes from step to step to step. Like this:

  • Ask a question. The question is 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.
  • Do experiments or make observations to test the hypothesis.
  • Gather the data.
  • Use logical reasoning to formulate a conclusion.

The process doesn’t always go in a straight line. A scientist might ask a question, then do some background research. He may then discover that the question needed to be asked a different way, or that a different question should be asked. He then goes back to the first step.

A flow chart of how science works that is much more accurate than the simple list above is found here: http://undsci.berkeley.edu/lessons/pdfs/complex_flow_handout.pdf .

Ask A Question

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

We learned in "Science is Based on Facts" that average global temperature has been rising since record keeping began in 1880. 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.

Atmospheric carbon dioxide has been increasing at Mauna Loa Observatory in Hawaii since 1958. The small ups and downs of the red line are due to changes in winter and summer. The black line is the annual average.

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

Answer a Question

So we’ve answered the question. We used data from research that has already been done. Fortunately, scientists have been monitoring CO 2 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.


  • greenhouse gas : Gases such as carbon dioxide and methane that absorb and hold heat from the sun’s infrared radiation in the atmosphere.
  • scientific method : A means of investigating a testable question using empirical information gathered from experiments, experience, or observations.


  • Scientists use scientific method to answer questions about the natural world.
  • First, scientists ask a question that they want to answer.
  • Background research is essential. It helps us to better understand the question. We can then move on to the next step.


Use this resource to answer the questions that follow.


  1. What is the first rule of writing science questions?
  2. What is rule number 2?
  3. What type of questions should NOT be used?
  4. What is rule number 3?
  5. Write a good scientific question using the three rules.


  1. What features does a question need to have to be a good science question?
  2. Create a question that is a good science question. Create a question that is not a good science question.
  3. Look at the graph of atmospheric CO 2 over time above . How much as the atmospheric CO 2 content risen since 1958?

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Jan 04, 2013

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Jan 15, 2016
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