Science as a Process
The Scientific
Method
The scientific method is a process for
experimentation that is used to explore
observations and answer questions.
Scientists use the scientific method to search
for cause and effect relationships in nature.
 What is cause and effect?

Step 1

Ask a Question: The scientific method starts
when you ask a question about something
that you observe: How, What, When, Who,
Which, Why, or Where? Typically, it is
measureable.
Criteria for Questions
Must be testable – an experiment can be
performed. “ Does the soil on Pluto contain
Iron?”
 Resource availability – can we actually do the
experiment with the materials you have. “Do
we have a spaceship that would take us to
Pluto?


Time – requires too much time “ Flying to
Pluto

Technology – do we have money and devices
necessary “ We can fly to other planets, but
do not have the technology to Pluto”
Step 2
Do Background Research: Rather than
starting from scratch in putting together a plan
for answering your question, you want to be a
savvy scientist using library and Internet
research to help you find the best way to do
things.
 Can you think of any other ways to get
research?

Step 3
Construct a Hypothesis: A hypothesis is an
possible explanation about how things work:
"If _____[I do this] _____, then
_____[this]_____ will happen."
 If I grow my plants under red lights, then the
plants will grow taller.

Step 4
Test Your Hypothesis by Doing an Experiment:
Your experiment tests whether your hypothesis is
true or false.
 It is important for your experiment to be a fair test.
You conduct a fair test by making sure that you
change only one factor at a time while keeping all
other conditions the same.
 You should also repeat your experiments several
times to make sure that the first results weren't just
an accident.

Designing your experiment
There are key things to remember while
designing an experiment.
 1. All experiments have 2 variables.
 The independent variable is the variable or
thing you are changing in the experiment.
For example the color of light used to grow
plants.


The dependent variable is the resulting
condition because of the independent
variable. It is always observable or
measureable. Example: Because of the red
lights on the plants, the plants grew taller.
Growing taller is the dependent variable.
Experiments also have controlled variables.
Controlled variables are quantities that a
scientist wants to remain constant, and he
must observe them as carefully as the
dependent variables.
 In our example, variables that would be
controlled are amount of water, fertilizer, time
exposed to light, type of plant, pot, and soil.
 Why are these variables so important?

An experiment will have two groups also.
 The experimental group consists of the trials
where you change the independent variable.
For example, if your question asks whether
red light makes a plant grow bigger, then the
experimental group consists of all trials in
which the plants are grown under red light.

In many experiments it is important to perform a trial
with the independent variable at a special setting for
comparison with the other trials. This trial is referred
to as a control group.
 The control group consists of all those trials where
you leave the independent variable in its natural
state. In our example, it would be important to run
some trials in which the plants get regular sunlight.
These trials with sunlight provide a basis for
comparison.

Step 5

Analyze Your Data and Draw a
Conclusion: Once your experiment is
complete, you collect your measurements
and analyze them to see if your hypothesis is
true or false
What is my problem
The school needs to know which brand of
paper towel is the most absorbent.
 Your task to figure this problem out by using
the scientific method.
 Three brands of paper towel will be provide
for you as well as beakers, cylinders, rulers,
scissors. If you need anything else, let me
know.

What information should I include
on my answer sheet?
Title of experiment:
 Observations:
 Hypothesis: I think _____ then_____
 Independent variable: What is different about the groups
 Dependent variable: What happens because of the
difference.
 Materials:
 Procedures: list steps
 Analysis: include charts, graphs you make
 Conclusion: Which one is the most absorbent?
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