Scientific Method

A. Defining Science

Pure Scienceresearch that adds to the body of scientific knowledge has no practical use

Applied Science (Technology)the practical application of scientific knowledge

A. Defining Science

PURE

human genetics

polymer science

atomic theory

study of the human ear

APPLIED

DNA fingerprinting

Lycra® spandex

nuclear weapons

hearing aids

A. Defining Science

Life Sciencethe study of living organisms

Earth Sciencethe study of Earth and space

Physical Sciencethe study of matter and energychemistry & physics

B. Problem-Solving

1. Identify the problem.What do you know?What do you need to know?

2. Plan a strategy.Look for patterns.Break the problem into smaller steps. Develop a model.

B. Problem-Solving

3. Execute your plan.

4. Evaluate your results.Did you solve the problem?Is your answer reasonable?

Identify - Plan - Execute - Evaluate

ObservationObservation

HypothesisHypothesis

ExperimentExperiment

Data Data CollectionCollection

ConclusionConclusion

RetestRetest

ObservationsObservations

Gathered through Gathered through your your sensessenses

A scientist notices A scientist notices something in their something in their

natural worldnatural world

ObservationsObservations

An An exampleexample of an of an observationobservation might be might be

noticing that many noticing that many salamanders near a salamanders near a

pond have curved, not pond have curved, not straight, tailsstraight, tails

HypothesisHypothesis

A suggested solution to A suggested solution to the problem.the problem.Must be Must be testabletestableSometimes written as Sometimes written as If…Then…If…Then… statements statementsPredictsPredicts an outcome an outcome

HypothesisHypothesis

An An example of a example of a hypothesishypothesis might be might be that the salamanders that the salamanders have curved tails due have curved tails due to a pollutant in the to a pollutant in the moist soil where they moist soil where they live. live.

ExperimentExperiment

A procedure A procedure to to testtest the the hypothesis.hypothesis.

ExperimentExperiment

VariableVariable – – factor in the factor in the experiment experiment that is being that is being

testedtested

ExperimentExperiment

A good or A good or “valid” “valid”

experiment experiment will only will only

have have ONE ONE variable!variable!

Controls and VariablesControls and Variables

Scientific Experiments Follow Scientific Experiments Follow RulesRules

An experimenter changes one factor and observes or measures what happens.

The ControlThe Control

The experimenter makes a The experimenter makes a special effort to keep special effort to keep other other factors constantfactors constant so that so that they will not effect the they will not effect the outcome.outcome.

Those factors are called Those factors are called controls.controls.

What is the Purpose of a What is the Purpose of a Control?Control?

Controls are NOT being testedControls are used for COMPARISON

Other Variables

The factor that is changed is known as the independent variable. (manipulated Varable)

The factor that is measured or observed is called the dependent variable or Responding variable).

Example of Controls & Example of Controls & VariablesVariables

For example, suppose you want to figure out the fastest route to walk home from school. You will try several different routes and time how long it takes you to get home by each one. Since you are only interested in finding a route that is fastest for you, you will do the walking yourself.

What are the Variables in Your What are the Variables in Your Experiment?Experiment?

Varying the route is the Varying the route is the independent variableindependent variable The time it takes is the The time it takes is the dependent variabledependent variable Keeping the same walker Keeping the same walker throughout makes the throughout makes the walker a walker a control.control.

One more thing… it is best to make several trials with each independent variable.

Valid ExperimentsValid Experiments

Remember: To be a Valid Remember: To be a Valid Experiment:Experiment:

Two groups are required --- the control & experimental groupsThere should be only one variable

DataDataResults of the experimentMay be quantitative (numbers) or qualitative

DataDataMust be organizedCan be organized into charts, tables, or graphs

ConclusionConclusion

The answer to the hypothesis based on the data obtained from the experiment

RetestRetest

In order to verify the results,

experiments must be retested.

Solving a ProblemSolving a Problem1) Make Observations

about a problem2) Form a Hypothesis

about the problem (if…then…)

3) Design an Experiment to test the hypothesis

4) Collect Data5) Form a Conclusion6) Retest