11Scientific Experiments Follow Rules An experimenter changes one factor and observes or measures what happens.
12The Control VariableThe experimenter makes a special effort to keep 1 factor the same or unchanged so that they will not effect the outcome.Those factors are called control variables.
13What is the Purpose of a Control? Controls are NOT being testedControls are used for COMPARISON
14Other VariablesThe factor that is changed is known as the independent variable.The factor that is measured or observed is called the dependent variable.
15You Are Already Scientists! 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.
16What are the Variables in Your Experiment? Different routes are the independent variable.(changing)The time it takes is the dependent variable (being measured)Keeping the same walker (yourself) throughout makes the walker a control variable.(used for comparison)
17One more thing… it is best to make several trials with each independent variable. The more data…the better.
18Valid ExperimentsMr. G exampleLochsa River MadnessClass example
19Remember: To be a Valid (Good) Experiment: Two groups are required --- the control & experimental groupsThere should be only one variable being tested.
20Data Is Results (recordings) of the experiment May be quantitative (numbers) or qualitative
21DataMust be organizedCan be organized into charts, tables, or graphs
22ConclusionThe answer to the hypothesis based on the data obtained from the experiment
23In order to verify the results, experiments must be retested. Publish and RetestIn order to verify the results, experiments must be retested.
24Publish in peer reviewed journal. Peer reviewed means that once your study is done, many other scientists with knowledge of your study go through how your experiment was performed. If they find ANYTHING wrong or untrue, the experiment is not published.Basically, a peer reviewed published study is very trustworthy.Problems with studies that aren’t peer reviewed?Hidden motives?
25Solving a Problem 1)Identify a Problem 2) State Observations about the problem3) Form a Hypothesis about the problem (if…then…)4) Design an Experiment to test the hypothesis5) Collect Data6) Form a Conclusion7) Retest