The Scientific Method 1

Observation

Observing – Using your senses to study objects

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Hypothesis A statement that can be tested

Forming a Hypothesis

Prediction A statement made in advance that states the results that will be obtained from testing the hypothesis Often in the form of an “if-then” statement

Experimenting

Testing a hypothesis or prediction by gathering data under controlled conditions

Measuring – Quantitative Numbers Sampling – Studying a small portion to represent the whole population

Independent Variable The factor being tested The only factor that can be changed in the experiment

Dependent Variable The factor being measured or observed –Result is “dependent” upon the independent variable

Controls A standard used for comparison. Controls do not have the independent variable applied to them

Constants Factors in an experiment that stay the same

Collecting Data

Analyzing Data Collected and organized data must be analyzed Process of determining whether data are reliable or whether they support or do not support a hypothesis or prediction

Inference Conclusions made on the basis of facts or premises rather than on direct observations –Often drawn from data gathered from an experiment or previous knowledge –Not directly testable –An ‘educated guess’

Forming a Theory An explanation supported by results of many experiments. Theories attempt to explain why something happens Supported by considerable evidence Ties together related hypotheses

Scientific Law Scientific law describes the behavior of something in nature. Laws predict or describe what will happen, but don’t always explain why it happens.

Communication Share the results of their studies with other scientists Publish findings in journals or at scientific meetings

OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat. HYPOTHESIS: Flies produce maggots. PROCEDURE Controlled Variables: jars, type of meat, location, temperature, time Manipulated Variables: gauze covering that keeps flies away from meat Uncovered jarsCovered jars Several days pass Maggots appear No maggots appear Responding Variable: whether maggots appear CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.