11 Scientific Experiments Follow Rules An experimenter changes one factor and observes or measures what happens.
12 The 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.
13 What is the Purpose of a Control? Controls are NOT being testedControls are used for COMPARISON
14 Other VariablesThe factor that is changed is known as the independent variable.The factor that is measured or observed is called the dependent variable.
15 You 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.
16 What 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)
17 One more thing… it is best to make several trials with each independent variable. The more data…the better.
18 Valid ExperimentsMr. G exampleLochsa River MadnessClass example
19 Remember: To be a Valid (Good) Experiment: Two groups are required --- the control & experimental groupsThere should be only one variable being tested.
20 Data Is Results (recordings) of the experiment May be quantitative (numbers) or qualitative
21 DataMust be organizedCan be organized into charts, tables, or graphs
22 ConclusionThe answer to the hypothesis based on the data obtained from the experiment
23 In order to verify the results, experiments must be retested. Publish and RetestIn order to verify the results, experiments must be retested.
24 Publish 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?
25 Solving 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