# Scientific Method - Polk County School District

Scientific Method Steps in the Scientific Method

Observation Hypothesis Experiment Data Collection Conclusion Retest Observations Gathered

through your senses A scientist notices something in their natural world Observations

An example of an observation might be noticing that many salamanders near a pond have curved, not straight, tails

Hypothesis

A suggested solution to the problem. Must be testable Sometimes written as If Then statements Predicts an outcome

Hypothesis An example of a hypothesis might be that the salamanders have curved tails due to a pollutant

in the moist soil where they live. Experiment A procedure to test the hypothesis .

Experiment Variable factor in the experiment that is being tested Experiment A good or

valid experiment will only have ONE variable! Controls and Variables Scientific Experiments Follow Rules

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

The Control Variable The experimenter makes a special effort to keep other factors constant so that they will not effect the outcome. Those factors are called control variables.

What is the Purpose of a Control? Controls are NOT being tested Controls are used for COMPARISON Other Variables

The factor that is changed is known as the independent variable. The factor that is measured or observed is called the

dependent variable. Example of Controls & Variables

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

One more thing it is best to make several trials with each independent variable. Valid Experiments Remember: To be a Valid Experiment: Two groups are required

--- the control & experimental groups There should be only one variable Data Results of the experiment

May be quantitative (numbers) or qualitative Data Must be organized Can be

organized into charts, tables, or graphs Conclusion The answer to

the hypothesis based on the data obtained from the experiment Retest In order to verify the results,

experiments must be retested. Review Solving a Problem 1)Identify a Problem 2) State Observations about the problem

3) Form a Hypothesis about the problem (ifthen) 4) Design an Experiment to test the hypothesis 5) Collect Data 6) Form a Conclusion 7) Retest

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