The Scientific MethodThe Scientific Method

Ch. 5Ch. 5

Forming a HypothesisForming a Hypothesis

HypothesisHypothesis = testable predictions = testable predictions that explain certain observations.that explain certain observations.

Hypothesis is an educated guess, together Hypothesis is an educated guess, together with observation, forming a hypothesis is with observation, forming a hypothesis is the first step in the scientific method.the first step in the scientific method.

Stating and writing your hypothesis gives Stating and writing your hypothesis gives you a goal and a focus.you a goal and a focus.

Reasoning SkillsReasoning SkillsInductive and DeductiveInductive and Deductive

Inductive reasoningInductive reasoning = drawing a general = drawing a general conclusion from specific facts or experiences.conclusion from specific facts or experiences.

Ex. if you wrapped muffins and a sandwich, which Ex. if you wrapped muffins and a sandwich, which becomes dry by lunchtime, you might conclude that the becomes dry by lunchtime, you might conclude that the plastic wrap is faulty.plastic wrap is faulty.

Deductive reasoningDeductive reasoning = You reach a = You reach a conclusion about a specific case based on conclusion about a specific case based on known facts and general principles.known facts and general principles.

Such reasoning is often expressed as “if….then” Such reasoning is often expressed as “if….then” statementsstatements

““If water expands when it freezes and my soft drink is If water expands when it freezes and my soft drink is mostly water, then the can could explode in the freezer” mostly water, then the can could explode in the freezer”

ExperimentationExperimentation

Experiments Experiments = A way to test a = A way to test a hypothesis in order to verify or hypothesis in order to verify or disprove it.disprove it.

Experiment includes a list of equipment and Experiment includes a list of equipment and materials, as well as a procedure that gives materials, as well as a procedure that gives step-by-step instructionsstep-by-step instructions

Carry out experiments in a logical, organized Carry out experiments in a logical, organized mannermanner

Because foods are not uniform in Because foods are not uniform in composition, your results may vary from composition, your results may vary from those of your classmatesthose of your classmates

Your observation may also lead you to form Your observation may also lead you to form a new hypotheses that will need to be tested a new hypotheses that will need to be tested by performing additional experimentsby performing additional experiments

Controlling VariablesControlling Variables VariablesVariables = factors that can change in an = factors that can change in an

experiment.experiment. By controlling all the variables except one, you get more By controlling all the variables except one, you get more

reliable results.reliable results. Ex. If you wanted to determine whether glass, plastic or Ex. If you wanted to determine whether glass, plastic or

metal bowls are best for whipping cream, what variables metal bowls are best for whipping cream, what variables could affect the outcome?could affect the outcome?

Bowl sizes and shapes; temperature of the whipping Bowl sizes and shapes; temperature of the whipping cream samples; types of beating device; the whipping cream samples; types of beating device; the whipping speed are just a few examples.speed are just a few examples.

Independent variableIndependent variable = this is a factor that = this is a factor that you change. Ex. would be the bowl materialyou change. Ex. would be the bowl material

Dependent variableDependent variable = is a factor that = is a factor that changes as a result of the independent changes as a result of the independent variablevariable

Analyzing DataAnalyzing Data Data Data = is the information gathered = is the information gathered

during an experiment.during an experiment.– The more consistent your data, the more The more consistent your data, the more

valuable it will be for drawing valuable it will be for drawing conclusions.conclusions.

– You may need to repeat an experiment to You may need to repeat an experiment to determine whether results are consistent.determine whether results are consistent.

– If the results are consistent, you may If the results are consistent, you may draw valid conclusions from them, draw valid conclusions from them, inconsistent or confusing results may inconsistent or confusing results may need to be repeated.need to be repeated.

Data TableData Table

Understanding, scientists arrange Understanding, scientists arrange data, they use charts, graphs, tables data, they use charts, graphs, tables and explanations.and explanations.

This experiments in this text suggest data This experiments in this text suggest data tables. Independent variables might be tables. Independent variables might be listed along on side of the table and the listed along on side of the table and the dependent variables on another.dependent variables on another.

Reporting ResultsReporting Results

The scientific method isn’t complete The scientific method isn’t complete without reporting the results of without reporting the results of experimentation. experimentation.

– To be accepted among scientists, an experiment To be accepted among scientists, an experiment must be reproducible.must be reproducible.

– Other scientists must be able to repeat the Other scientists must be able to repeat the experimentexperiment

– Because scientific questions can be complicated, Because scientific questions can be complicated, hypotheses may have to be tested with many hypotheses may have to be tested with many experiments to determine whether they are valid.experiments to determine whether they are valid.

– Some hypothesis are tested for years.Some hypothesis are tested for years.

Report FormReport Form

Developing and Revising Developing and Revising TheoriesTheories

““No amount of experimentation can No amount of experimentation can ever prove me right; a single ever prove me right; a single experiment can prove me wrong.” experiment can prove me wrong.” Albert EinsteinAlbert Einstein

A hypothesis that is consistently verified may A hypothesis that is consistently verified may be established as a theory.be established as a theory.

TheoryTheory = an explanation based on a = an explanation based on a body of knowledge gained from many body of knowledge gained from many observations and supported by the observations and supported by the results of many experiments.results of many experiments.

A hypothesis is a possibility; a theory is a A hypothesis is a possibility; a theory is a probability.probability.

Conducting ResearchConducting Research

The scientific method benefits from The scientific method benefits from research, investigating what others research, investigating what others have learned about a subject.have learned about a subject.

Every research project starts with a Every research project starts with a topictopic

(pick a topic that interests you, start your (pick a topic that interests you, start your questions in the supermarket)questions in the supermarket)

Narrowing the Focus – Narrowing the Focus – Come up with an experiment, or a question Come up with an experiment, or a question

that you would like to answer? that you would like to answer?

Observation

Observation

Observation

Experiments

Theory

Experiments

Revised Theory

Hypothesis

Revised Hypothesis

THE SCIENTIFIC METHOD

After you experiment, you might

need to revise your theory.

This could continue, until

you are satisfied with the outcome.

Dairy Products

Food and Nutrition

Grains

Milk in the diet

Vitamins and minerals

Wheat

Lactose intolerance

Vitamin C

Chemistry of gluten

Finding InformationFinding Information

Exploring a new field begins by Exploring a new field begins by reviewing already existing literature.reviewing already existing literature.

To gather information you could start wit the To gather information you could start wit the Reader’s Guide to Periodical Literature for Reader’s Guide to Periodical Literature for recent magazine articles.recent magazine articles.

Journals such as FDA Consumer, Journal of Journals such as FDA Consumer, Journal of Food Science, Food Technology, Food Food Science, Food Technology, Food Engineering, or Journal of the American Engineering, or Journal of the American Dietetic AssociationDietetic Association

QuestionsQuestions

1.1. Describe the value of the scientific method.Describe the value of the scientific method.2.2. What is the purpose of a hypothesis in What is the purpose of a hypothesis in

experimentation?experimentation?3.3. Suppose your car stops running and you notice Suppose your car stops running and you notice

the gas gauge is on “empty.” Write one the gas gauge is on “empty.” Write one statement showing inductive reasoning and one statement showing inductive reasoning and one showing deductive reasoning based on this showing deductive reasoning based on this event.event.

4.4. Name two possible variables in an experiement Name two possible variables in an experiement to test the cleaning ability o two laundry to test the cleaning ability o two laundry detergents.detergents.

5.5. Why is it unwise to change more than one Why is it unwise to change more than one variable in an experimental trial.variable in an experimental trial.

Questions ContinuedQuestions Continued

6.6. What is the point in repeating an experiment?What is the point in repeating an experiment?7.7. How is reporting results of experimentation in a How is reporting results of experimentation in a

journal different from reporting facts in a data journal different from reporting facts in a data table?table?

8.8. Why is filling out an experiment report form helpful Why is filling out an experiment report form helpful for learning?for learning?

9.9. Is it considered appropriate to doubt an accepted Is it considered appropriate to doubt an accepted theory? Explain.theory? Explain.

10.10. Explain which topic would be more suitable for a Explain which topic would be more suitable for a research paper: the manufacture of steel; or new research paper: the manufacture of steel; or new uses for computers in the manufacture of steel.uses for computers in the manufacture of steel.

11.11. What people might be helpful as you undertake a What people might be helpful as you undertake a food science research project?food science research project?