THE SCIENTIFIC METHOD
Scientists, like most people, try and use a common sense approach to solving problems.
This approach is logical and systematic and is sometimes called the scientific method.
What is the scientific method?
The following steps have been found useful in working out the solution to problems.
1. Understand the problem
After making observations, you realize that there is something you do not know
or understand. As a result, you wonder why something happens as it does. You need to
state the problem facing you clearly in the form of a question. Recall your inquiry
investigation at the beginning of this unit. You made observations about the beaker.
Then you may have wondered if here was something inside the beaker. Observing the
beaker and thinking about the situation might have led you to state the problem in the
form of a question: Is the beaker empty or is it full of something?
2. Collect information
The first thing you need to do to answer your question is conduct research. Refer
to books and other written materials that relate you your problem. You may want to
interview people with knowledge of your problem. It is possible that someone else may
have information concerning the same problem. The information you gather may
provide you with clues that can help you find a way to answer your question.
3. Form a hypothesis
A hypothesis is a suggested solution to a problem or a possible answer to your question.
A hypothesis is not a wild guess. It should be based on the information you collected
and the observations you made. Keep in mind that an observation is information you
gather using your senses. There are two types of observations. The first one is known
as quantitative observations, which use numbers, and are often a measurement of some
kind. The second type of observation is known as qualitative observations, which are
gathered by using the five senses. Some examples of qualitative observations are color,
texture, aroma and flavor. Learn to be a careful observer. In the case of the inquiry
investigation, your hypothesis might have been: If the beaker is open in a room filled
with air, then the beaker is also filled with air.
4. Test the Hypothesis
It is necessary to design and carry out an experiment that will test the hypothesis. The
sign of a good hypothesis is that it can be tested. There must be a possible answer that
can be shown to be true or false. It is not enough to say, “It’s obvious that the bottle is
full of air.” You must obtain scientific evidence.
The steps that you follow to test a hypothesis are known as the procedure. You must
write the procedure in such a way that someone else could repeat the same experiment
in exactly the same way. You need to include the materials you used, the amount or
size of each material, and what you did with the materials in the order you did it.
5. Keep a record of your experiment
As you carry out an experiment, observe carefully and record your observations, or
data, in a laboratory notebook. Be sure to write the date and time of the observation
and the conditions under which it was made. Do not try to remember what you
observed and wait to write it down at a later time. You must record your data as you
gather it. You can always go back and present your data in a way that makes it easier to
follow. For example, you might arrange numerical data in a table or graph. You might
present other kinds of data in a diagram or map.
6. Analyze the results
Once you have data from your experiment, you need to study it to figure out what it
shows. When data consists of numbers, you might look for patterns and trends. In
other words, are values increasing, decreasing or staying the same? Once you analyze
the results, you can reach a conclusion, which is a statement indicating if the hypothesis
was supported by the data. A conclusion is a kind of inference, which is a statement
based on a series of observations. An inference is an attempt to explain why the
observations occurred. An example of an inference follows: “the beaker was not able to
fill with water so there must be air in the space where the water did not go.”
If the data does not support the hypothesis, the hypothesis must be rejected. Do not
consider this a failure. Showing that the hypothesis is not correct provides new
information. It guides you to develop and test a new hypothesis. That is part of the
process of scientific inquiry. Scientific inquiry is the nature of scientific thinking and the
process scientists use to solve problems.
7. Repeat the experiment
In any experiment, it is always possible that some error was introduced. To avoid
“jumping to conclusions,” you should repeat your experiment as many times as possible.
If you, or someone else, can duplicate the results of your experiment with little or no
change, your conclusions are probably valid. Results that are valid are reasonable,
logical, and can be achieved by repeated testing. This is another reason why your
procedure needs to be well- written. Other people need to be able to repeat your
experiment to confirm your results.
8. Confirm the conclusion
Repeating an experiment and getting the same results is one way to confirm the
conclusion. Another important method of confirming a conclusion is to try to use the
information revealed by the experiment to explain other related problems. If
successful, you can be more certain that the conclusion is reasonable.
9. Communicate the results to others
It is important for others to know what you have learned so that they will be able to
confirm your results and possibly use them to solve other problems. Scientists publicize
their findings in several ways, such as writing reports in magazines known as scientific
journals or giving lectures to other scientists at professional meetings.
10.Identify new problems for investigation
Scientific knowledge has grown because the solution to one problem often leads to the
investigation of new problems. For example, you showed that the “empty” beaker
actually contained a gas. The next logical step would be to show that the gas is air.
HOW ARE THEORIES DEVELOPED?
After scientists have performed many experiments, made many observations, and
tested several hypotheses, they may try to provide an explanation of their results that can be
applied to related situations. They do this by formulating a theory. A theory is a detailed
explanation of large bodies of information, represents the most logical explanation of the
evidence, and is generally accepted as fact (unless shown to be otherwise). Theories are often
revised as technology improves and new observations are made. Most theories are based on
the work of many scientists over a long period of time and become stronger as more
supporting evidence and experimental data are gathered.
No single experiment can prove that a theory is correct. The experimental results can
support only the possibility that the theory is right. However, a single experiment can prove a
theory wrong if the results do not support the theory.
What are variables and controls?
Experiments must be conducted in an organized way so that you can reach valid results.
Two important considerations for obtaining valid results are variables and controls.
What are experimental variables?
Any conditions that can be changed during an experiment are called variables. In an
experiment, you need to keep all but one of the variables constant, or unchanged. The one
variable that you change is the independent variable. The hypothesis should relate these two
variables. Suppose, for example, you want to find out how the height from which you drop a
ball affects the height to which it bounces. Your hypothesis might be: if the height from which
a ball is dropped increases, the height to which the ball bounces will increase. The starting
height would be the independent variable and the height to which the ball bounces would be
the dependent variable.
Would it be a good experiment to drop a golf ball, a tennis ball, and a basketball from
different heights in different places to observe how they bounce in order to test the
hypothesis about height? No. All the balls bounce differently, so you will not know if it was
the type of ball, the surface on which it bounced, or the height from which it was dropped that
affected the height of the bounce. An experiment must have only one independent variable;
otherwise, the results cannot be attributed to a single cause.
What are controlled experiments?
In order for the results of an experiment to be useful, they must be compared with
some standard that does not change during the experiment. For example, suppose a teacher
wants to find out if listening to classical music helps students perform better on exams. The
teacher gathers a group of students for an exam. Should the teacher let all the students listen
to music while taking the exam? If the teacher lets all the students listen to music and finds
that most do well on the exam, the teacher cannot be sure if the change was because of the
music. There might have been some other variable that affected all the students. For
example, the exam might have been easier than usual, or it might have been on a topic that
students find interesting.
To establish something for comparison, the teacher needs to have only some of the
students listen to music during the exam. Then, if all the students do well on the exam, the
teacher knows it was not because of the music. If instead, the students who listened to music
did substantially better on the exam than the other students, the teacher can conclude that it
was because of the music. The group of students who were not allowed to listen to music is
known as the control for this investigation.
How can you use the Scientific Method in everyday life?
You might be surprised to find out that you use the scientific method even when you are
not in science class. The work of science requires a variety of abilities and qualities that are
helpful in daily life. Suppose for example, you have a cell phone that stops working. Perhaps
you have been in that situation before, so you assume the battery needs to be charged. After
plugging it into the charger, you find that the phone still does not work. What do you do next?
Before you give up on your cell phone, you would probably analyze the situation more closely.
You might ask some friends who have similar cell phones if they have ever had the same
problem. You might then go on line to search the information at the manufacturer’s Web site.
There you might discover that other people have reported that their chargers stopped
working, which might lead you to consider that your charger has stopped working as well. To
check, you find a friend who has a working charger and use it to charge your cell phone. Your
phone works fine! You buy a new charger and your problem is solved.
What does this example have to do with the scientific method? You will see if you think
about the example in scientific terms. You made an observation that your cell phone did not
work. Then you conducted research to investigate the problem. Based on your research, you
made a hypothesis about the charger being the cause of the problem. Then you performed a
test to evaluate your hypothesis. The test led you to reach a conclusion which you explored by
trying another charger.
This is just one of the many examples you could consider to realize that you use the
scientific method every day. Thinking scientifically is a useful way to solve problems and can
be applied to common situations.