The Scientific Method

On this page:

  • Explanation of how the scientific method works
  • Hypotheses, theories, and laws
  • Basic and applied research
  • Practice worksheets that allow you to test your knowledge
  • Miscellaneous questions other people have asked me about the scientific method

What is the scientific method?

The scientific method is a set of guidelines that scientists agree should be followed to ensure high quality scientific investigation.  These guidelines include the following:

  • Scientific studies must be unbiased.  It’s well-known that scientists have pressure applied to them by the people who fund them, by their research institutions, and by their spouses who have been patiently waiting for a Nobel Prize.  To keep these pressures from screwing up our data, experiments are typically designed such that the experimenters simply can’t interfere with them much (most common example:  double-blind studies in medical research).
  • Scientific studies must be methodical.  When you do science stuff, you need to make sure that all of the variables are controlled except for the one that you’re manipulating.  Otherwise, you won’t know what caused the effect you observe.
  • Scientific studies must use reasonable and widely-accepted methods for gathering data.  If you are trying to tell the world that you were able to make medicine B with 95% purity, it won’t be very convincing if you tell them that an angel told you how pure it was, or that the guy down the hall “had a feeling that it would work.”  In those cases where new methods are developed, there needs to be justification for using these methods, as well as good reasons why they can be trusted.
  • Scientific studies must be reproducible.  If nobody but you can make the experiment work, chances are good that the phenomenon doesn’t really exist.  (An excellent article outlining what happened in “cold fusion” research when experimenters couldn’t reproduce the claimed results).
  • Scientific results must be peer-reviewed.  For anybody to take you seriously, you need to get a panel of experts in your field to examine your paper for flaws before publication.  By paying attention to others in the field (both reviewers and readers), bad ideas are killed and good ones are further developed. (A thoughtful article about peer-review).

How do I use the scientific method?

The easiest answer is to just do the stuff above.  If you do all of that, you’re officially a scientist. However, teachers generally like you to do things in a more formal manner, particularly since it’s easier to make sure you actually do the right thing that way.  Plus, it’s easier to grade.

The steps of the scientific method include:

  • Purpose:  This is your reason for doing an experiment.  Do you want to see if medicine A cures athlete’s foot? Do you want to make an explosive that will selectively kill squirrels?  Do you want to make a new material that’s invisible to light but still shows up on those fancy police helicopter cameras?  That’s your purpose for doing the experiment.
  • Hypothesis:  Because you can’t cure cancer or make a cool explosive in one experiment, your hypothesis will focus on one small aspect of what you’re doing.  This will be in the form of an “if ___”, “then ___” statement in which the “if” part indicates what you’re going to be trying to do and the “then” part indicates what you think the outcome will be.  The variable you’re changing will be the independent variable, and the thing that happens during the experiment is the dependent variable.
  • Materials:  This is a list of the stuff you’ll be using in the experiment.  Be as specific as possible, and be sure to indicate the quantities of each material or piece of equipment used.  If you need to cross something out and write something else in because you altered your experiment, it’s generally OK to do so as long as you initial the change and put a date next to it.
  • Procedure:  This is a complete description of everything you do in the experiment.  If you need to draw pictures to show the apparatus you’ve used, do it here.  Though some teachers would like you to make the procedure so clear that even the stupidest human being alive can follow the steps, you can usually make the more reasonable assumption that you’re writing the procedure for somebody slightly less experienced than yourself.
  • Results:  These are your raw data (yes, data is a plural word, not singular as you’ve probably been taught).  If you measured that something burst into flames, write it down.  If you got 45 grams of product, write it down.  Whatever happens, write it down.  The two forms of data you will be using include qualitative data (non-numerical descriptions of what happened, such as “it turned blue and burned like crazy”) and quantitative data (measured, numerical values, such as “it weighed 45 grams and reached a temperature of 77 degrees).  No experiment is complete without both forms of data.
  • Conclusion:  Did the experiment work?  The first sentence should stand by itself and be a “when ___, then ___” statement in exactly the same format as the hypothesis.  For example, if the hypothesis was “when I poke my sister, then she will get mad”, the conclusion might be “when I poked my sister, then she got mad.”  After you’ve written this statement, it’s time to explain your justification for making this statement to the world.  But keep it short.

An example of the scientific method:

  • Purpose:  To find out if my son will get mad when I eat his candy.
  • Hypothesis:  If I eat my son’s candy, then he will become upset.
  • Materials:  My son, one lollipop
  • Procedure:  Tell my son that he got a piece of candy.  Pull out lollipop. Eat lollipop. Record results.
  • Results: My son was upset, screaming for five minutes and sobbing for another ten minutes.  My wife was also upset, calling me a “jerk” and indicating that “I should never have married you.”  I was told to apologize to my son.
  • Conclusion:  When I eat my son’s candy, then he becomes upset.

Note:  This is an illustration of the scientific method, not an indication that I’ve taunted my son in this fashion


Hypotheses, theories, and stuff like that:

When somebody is trying to figure out the answer to a problem, they try to solve it.  Or if they’re lazy, they watch TV.  We’re not here to judge.

If a scientist wants to figure out the answer to a problem, they’ll come up with a hypothesis about the thing they’re interested in.  This hypothesis is an educated guess about what’s happening, and is something that can be tested with an experiment.  If something can’t be tested with an experiment, it’s not something that qualifies as science.

If the hypothesis seems to work, the scientist might have enough information to build a model that explains the phenomena.  Models are collections of ideas that provide a framework for explaining why and how things happen.  Further testing of this model using different hypotheses is then required to see if the model is actually any good.

When experiments show that the model seems to work, the model becomes a theory. Though the word “theory” is sometimes misinterpreted as meaning “educated guess”, theories are actually widely-accepted and widely-supported ideas that accurately describe the phenomenon they describe.  For example, when people refer to evolution as being a theory, they’re not saying that it is an idea that some people have put forth; they’re saying that it’s an idea that has been supported by the available scientific evidence and is generally supported by the scientific community.

You may have noted that some things are referred to as laws.  Laws are very simple statements that describe how a wide variety of phenomena will behave under some set of conditions.  For example, the law of conservation of mass says that you can neither create mass from nothing nor make it vanish completely.  Though not as fancy as a theory, you can pretty treat a law as being true in all circumstances.


Why people do research in the first place

Because lots of people have lots of problems, there are lots of scientists doing lots of research. Some of this research is really cool, while other experiments are boring. Either way, there are a lot of things to discover, and as long as the checks continue to clear, there will be scientists to discover them.

Here are the main reasons that research is performed:

  • Pure research occurs when people try to figure stuff out just for fun. Lots of pure research is done at universities, where graduate students study things they don’t really care about so they can one day get academic jobs and make their students study things they don’t care about.
  • Applied research is when scientists are given a problem and told to solve it. This happens in industry, where the people in charge hope to make a bucket of money off of the scientists’ discoveries.

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This webpage and the scientific method worksheet are both licensed under the Creative Commons Attribution-NonCommerical-ShareAlike 4.0 International license (CC BY-NC 4.0).  For more information about this license and how it affects how you can use the contents of this site, click here.

The links in the body of the text and the link to Mr. Nye’s video are not covered under this license and the copyright holder should be contacted directly for their terms of use.

 

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