2. Key steps of scientific investigation
Science is devoted to discovering general principles that govern our physical world.
Scientists often follow what is called the ‘Scientific Method’ when conducting a
scientific investigation. Scientific Investigation involves a set of outlined procedures.
Although all experiments do not follow the same steps in the same order, many follow
a pattern similar to the one described here:
On the basis of observations and previous data, a scientist formulates a hypothesis.
The hypothesis is tested by further observations or experiments, and new data either
support or falsify the hypothesis. Indeed, a scientist often chooses to retest the same
hypothesis or to test a related hypothesis. Conclusions from many different but related
experiments may lead to the development of a scientific theory.
Making Observations
Scientific investigation is limited to questions that can be studied by direct or indirect
observations. An observable event is called a phenomenon. Observations can be made
by any one of our five senses including sight, hearing, touch, smell and taste. We can
observe with our fingertips that a surface is smooth and cold, and observe with our
ears that a piano needs tuning. Various inputs allow scientists to formulate hypothesis.
Questioning and Exploration
As scientists gain more empirical evidences about an event, they begin to develop
questions about it. How does this happen? What causes it to occur? When will it take
place again? A question that is too broad or too complex may be impossible to answer.
Once a decision has been made about what question to ask, scientists explore other
sources of knowledge to gain more information. Perhaps the question has already
been answered by someone else or several possible answers have already been
rejected. Scientists will read appropriate scientific publications, explore information
on the Internet, or consult fellow scientists who are interested in the same field of
study to avoid investing time in repeating research that has been done. As a result of
this activity, a decision is made about whether to continue exploring the question.
Formulating a Hypothesis
Once a scientist becomes interested in an observable event, he or she will most likely
follow up with it. A hypothesis is a tentative explanation of a scientific question based
on observations and past knowledge. It is a statement of what you should observe in
the natural world if you were to look for it. This is often called the ‘if-then’ process.
Hypotheses vary in the level of their sophistication. A young person in elementary
school might hypothesize that plants need light in order to grow, while a high school
student might hypothesize that lights allows plant leaves to produce sugar. In all cases,
all the past experiences of individuals, no matter where their sources are, will most
likely influence the formulation of a hypothesis.
Formulating a hypothesis involves inductive reasoning. Using isolated facts to
generalize an observed phenomenon is called inductive reasoning. For example, if
gravity does not pull objects toward the Earth, then it should be possible to observe
apples ‘falling’ up, but not down, from a tree.
Testing a Hypothesis
Scientists consider hypotheses that can be tested either in a laboratory or in a natural
setting or by observation.
 Experimentation
A laboratory is a place that allows scientists to carry out experiments, it is an artificial
situation devised to test hypotheses. Laboratory experiments are often preferred
because a laboratory setting eliminates extraneous variables.
 Field Testing
Experiments can also be carried out under a natural setting called a field. A variable is
a factor that can cause an observable change. A controlled experiment has a control
group that does not experience the tested variable. This eliminates the possibility that
the results are due to non-identifiable changing events.
Sample drawn from some aspects of nature
Experimental Group (variable
being tested is present)
Results complied
Control Group (variable
being tested is absent)
Results complied
Test results are compared and analyzed
Experimental designs and results are reported,
and the conclusions are drawn from them
 By Observations
Some investigations are based on observations rather than experimentations. All the
above scientific steps previously listed can still be applied.
Testing Results
The results of an experiment are referred as data. Data should be objective rather than
subjective, and mathematical data are conductive to objectivity. To ensure that the
results are not due to random chances or some unknown variables, an experiment is
often repeated not only by the original scientists but also by other people who are in
the same area of expertise. If the same results are not obtained over and over again,
the experiment is not considered to be valid.
Conclusion
After studying the results, the experimenters come to a conclusion whether the results
support or falsify the hypothesis. Scientific progresses and hypothesis may have to be
modified in the future. There is always a possibility that a more sophisticated
experiment using perhaps more advanced technology might falsify the hypothesis.