THE SCIENTIFIC METHOD
Science is a systematic process in which observation of the natural world leads to questions, and
possible answers to such questions are proposed and tested. This process of questioning and
investigation is known as the scientific method. The steps in the scientific method are as
follows:
1) Observe. The process begins with the observation of some phenomenon in the natural world.
Observations must be occurrences that we can see, feel, hear, touch, smell, or measure using
scientific tools (like telescopes or microscopes). Anything that cannot be directly observed in this
way is outside of the realm of science.
2) Formulate a question. This is the step that logically follows an observation that cannot be
readily explained. It usually takes the form, “I wonder if….?”, or “Could it be because….?”
3) Research the known facts. Often, it is not necessary to start at square one when investigating a
problem. Some questions that result from observations will have been investigated many times
before, and you can use that information to answer your question, or help focus your next step in
this process.
4) State a hypothesis. (Or, even better, multiple working hypotheses.) A hypothesis is a tentative,
testable statement relevant to answering the question you have asked about the phenomenon you
observed. The key part of this definition is testable. If a hypothesis cannot be tested, it is not
scientifically useful, no matter how interesting it might seem.
5) Test the hypothesis. This step involves the development of observations, experiments, and
models to test whether or not the hypothesis correctly explains all observed cases, and can be
used to correctly predict future outcomes. An important feature of such testing is that it must be
repeatable, not just by the original experimenter, but by others. Hypotheses are usually tested
many times.
6) Accept, modify, or reject the hypothesis. Many hypotheses are correct, and many are wrong.
Not supporting a hypothesis is not a scientific failure. Even hypotheses that are initially accepted
must often later be modified, or even totally rejected, when new observations come to light. It is
only after extensive testing that a hypothesis is elevated to the next level. A hypothesis that has
undergone extensive, rigorous testing may be advanced to the status of a theory, a statement or
relationship that is accepted by most scientists. Examples would be the theories of evolution and
plate tectonics. It is a common misconception on the part of non-scientists that the word “theory”
implies a highly speculative, tentative concept (i.e., just a “guess”). On the contrary, a hypothesis
only becomes a theory after years of testing and verification. The highest status a scientific
principle can achieve is a law. Laws are principles explaining events in nature that have been
observed to occur with unvarying consistency. Examples would be the laws of motion and
thermodynamics in physics.
Does science ever arrive at the undisputed “truth”? Any scientist who makes such a claim about
a scientific statement should be considered misguided. Absolute truth is not a reachable goal in
science, because we can never be sure that we have acquired and fully examined all available
data. No rational scientist will ever claim that he or she has enough data and needs no more. It is
even possible that well-accepted theories and laws may be superseded by new observations that
are not yet available. This should not, however, be looked upon as a weakness of science.
Instead, it is a great validation of the strength of the scientific method. Many of the greatest
scientific advancements in history have been the result of new observations that caused a
previously accepted hypothesis to be rejected.
The following exercises will acquaint you further with the scientific method.
Name: ______________________________Due at the start of lecture one week from today
Part 1 – Harold and the Orange Lake
The following exercise is designed to give you some practice in determining what are
appropriate scientific questions to ask and proper hypotheses to propose when faced with a
problem in the natural world.
Here’s the situation. On his way back to campus, driving across the I-90 bridge from Seattle,
Harold comes out of the tunnel and suddenly notices that Lake Washington has turned bright
orange. Several thoughts run through his mind. Some of these thoughts may be valid steps in
initiating the scientific method to solve this mystery, and some may not. Each may be classified
as one of the following:
a. An irrelevant observation (has no bearing on the problem)
b. A valid observation
c. An irrelevant question (has no bearing on the problem)
d. A valid question
e. An improper hypothesis (untestable)
f. A valid hypothesis (testable)
1) For each of the following thoughts that runs through Harold’s mind, specify (in the blank)
which of the above (a-f) best describes the statement.
_______ “Hey, the lake is orange!”
_______ “I like orange juice.”
_______ “Nothing else looks unusual, just the lake.”
_______ “I don’t smell anything unusual.”
_______ “What made the lake turn orange?”
_______ “Will Maude sit next to me in math class today?”
_______ “When did the lake turn orange?”
_______ “Is the water warmer or colder than usual?”
_______ “Aliens must have turned the lake orange using some kind of color laser beam.”
_______ “There must be some form pollution that has turned the lake orange.”
2) If you determined that any of the above were scientifically improper hypotheses, explain why
you thought so.
3) Is it possible for a hypothesis to be judged as a scientifically improper hypothesis, yet turn out
to be ultimately true? Why or why not?
Part 2 – Plants and Salt (a little more realistic scenario)
In this part, you will be given the initial observations, and asked to propose a question,
hypothesis, and experimental design to address the problem.
Here’s the situation: On a walk down to the beach, you observe that the plants change as you get
closer to the ocean and finally no plants grow when you get to the beach itself. You also observe
that there are salt crystals in the soil close to the beach, but not farther away from it.
1. Formulate a valid question based on the observations listed above.
2. State a proper scientific hypothesis based on your observations and the question you asked
above. Remember that it must be testable.
3. Propose an experiment that would test your hypothesis. What sort of data would you collect,
and how would you analyze it? Would you gather data in the field, or would you conduct a
laboratory experiment, or both? Why? Remember that a valid experiment should be free from
any bias (should not be set up to favor any particular outcome). Also such an experiment must be
repeatable (by you and by others).