The Scientific Method
Ch. 5
Forming a Hypothesis

Hypothesis = testable predictions that
explain certain observations.
 Hypothesis is an educated guess, together with
observation, forming a hypothesis is the first step
in the scientific method.
 Stating and writing your hypothesis gives you a
goal and a focus.
Reasoning Skills
Inductive and Deductive

Inductive reasoning = drawing a general
conclusion from specific facts or experiences.
 Ex. if you wrapped muffins and a sandwich, which becomes
dry by lunchtime, you might conclude that the plastic wrap is
faulty.

Deductive reasoning = You reach a
conclusion about a specific case based on known
facts and general principles.
 Such reasoning is often expressed as “if….then” statements
 “If water expands when it freezes and my soft drink is mostly
water, then the can could explode in the freezer”
Experimentation

Experiments = A way to test a
hypothesis in order to verify or disprove it.
 Experiment includes a list of equipment and
materials, as well as a procedure that gives stepby-step instructions
 Carry out experiments in a logical, organized
manner
 Because foods are not uniform in composition,
your results may vary from those of your
classmates
 Your observation may also lead you to form a new
hypotheses that will need to be tested by
performing additional experiments
Controlling Variables

Variables = factors that can change in an
experiment.
 By controlling all the variables except one, you get more
reliable results.
 Ex. If you wanted to determine whether glass, plastic or
metal bowls are best for whipping cream, what variables
could affect the outcome?
 Bowl sizes and shapes; temperature of the whipping cream
samples; types of beating device; the whipping speed are
just a few examples.

Independent variable = this is a factor that
you change. Ex. would be the bowl material
 Dependent variable = is a factor that changes
as a result of the independent variable
Analyzing Data

Data = is the information gathered during
an experiment.
– The more consistent your data, the more
valuable it will be for drawing conclusions.
– You may need to repeat an experiment to
determine whether results are consistent.
– If the results are consistent, you may draw
valid conclusions from them, inconsistent or
confusing results may need to be repeated.
Data Table

Understanding, scientists arrange data,
they use charts, graphs, tables and
explanations.
 This experiments in this text suggest data tables.
Independent variables might be listed along on
side of the table and the dependent variables on
another.
Reporting Results

The scientific method isn’t complete
without reporting the results of
experimentation.
– To be accepted among scientists, an experiment must be
reproducible.
– Other scientists must be able to repeat the experiment
– Because scientific questions can be complicated,
hypotheses may have to be tested with many
experiments to determine whether they are valid.
– Some hypothesis are tested for years.
Report Form
Developing and Revising Theories

“No amount of experimentation can ever
prove me right; a single experiment can
prove me wrong.” Albert Einstein
 A hypothesis that is consistently verified may be
established as a theory.

Theory = an explanation based on a
body of knowledge gained from many
observations and supported by the results
of many experiments.
 A hypothesis is a possibility; a theory is a
probability.
Conducting Research
The scientific method benefits from
research, investigating what others have
learned about a subject.
 Every research project starts with a topic

 (pick a topic that interests you, start your
questions in the supermarket)
 Narrowing the Focus –
 Come up with an experiment, or a question that you
would like to answer?
THE SCIENTIFIC METHOD
Observation
Observation
Observation
Hypothesis
After you
experiment, you
might need to
revise your
theory. This
could continue,
until you are
satisfied with the
outcome.
Experiments
Revised Hypothesis
Theory
Experiments
Revised Theory
Dairy Products
Milk in the diet
Food and Nutrition
Grains
Vitamins and
minerals
Wheat
Lactose intolerance
Vitamin C
Chemistry of gluten
Finding Information

Exploring a new field begins by reviewing
already existing literature.
 To gather information you could start wit the
Reader’s Guide to Periodical Literature for recent
magazine articles.
 Journals such as FDA Consumer, Journal of Food
Science, Food Technology, Food Engineering, or
Journal of the American Dietetic Association
Questions
1.
2.
3.
4.
5.
Describe the value of the scientific method.
What is the purpose of a hypothesis in
experimentation?
Suppose your car stops running and you notice the gas
gauge is on “empty.” Write one statement showing
inductive reasoning and one showing deductive
reasoning based on this event.
Name two possible variables in an experiement to test
the cleaning ability o two laundry detergents.
Why is it unwise to change more than one variable in
an experimental trial.
Questions Continued
6.
7.
8.
9.
10.
11.
What is the point in repeating an experiment?
How is reporting results of experimentation in a
journal different from reporting facts in a data table?
Why is filling out an experiment report form helpful for
learning?
Is it considered appropriate to doubt an accepted
theory? Explain.
Explain which topic would be more suitable for a
research paper: the manufacture of steel; or new uses
for computers in the manufacture of steel.
What people might be helpful as you undertake a food
science research project?