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Scientific Method

The goal of science is to answer questions about the natural world using the scientific method, which includes hypotheses and experiments to arrive at a conclusion.

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Scientific Questions

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?


  • scientific method: A way of investigating a testable question using information gathered from experiments, experience, or observations.
  • testable (question): A testable question is one that can be answered by collecting evidence.
  • greenhouse gas: Gases such as carbon dioxide and methane that absorb and hold heat from the sun’s infrared radiation in the atmosphere.

The Purpose of Science

The purpose of science is to answer questions about the natural world. 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 scientific question because can be answered by collecting and interpreting data, by studying the age of rocks, for example. The second cannot be answered using data, so it is not a scientific question.  We do not have any real data about the size of angels, or if they even exist.

Scientific Method

Scientists often use the scientific method to answer questions. The scientific method is a series of steps that help to investigate a question.

Often, students learn that the scientific method is a linear process that goes like this:

  • Make obesrvations about the world.  It is hard NOT to do 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.
  • Do experiments or make observations to test the hypothesis.
  • Gather the data.
  • Formulate a conclusion by looking at the evidence you collected.

The process doesn’t always go in a straight line. A scientist might ask a question, then do some background research and discover that the question needed to be asked a different way, or that a different question should be asked. Or that the answer is already known.

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 above that average global temperature has been rising since record keeping began in 1880. We 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.  Often scientific questions lead to other questions.  Another question that is important to science is whether there is a connection between the level of carbon dioxide and the rising temperatures.

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

How has carbon dioxide in the atmosphere changed over those 50-plus years? About how much has atmospheric CO2 risen between 1958 and 2011 in parts per million?

Answer a Question

So we’ve answered the question using data from research that has already been done. If scientists had not been monitoring CO2 levels over the years, we’d have had to start these measurements now.

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


  • Scientists can use the scientific method to answer questions about the natural world.
  • First, scientists ask a question that they want to answer.
  • Background research is essential for better understanding the question and being able to move 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.

Review Questions

  1. What features does a question need to have to be a good science question?
  2. Create a list of three questions that are good science questions. Create a list of three questions that are not science questions.

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