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 other factors constant so that they will not effect the outcome.
13 What is the Purpose of a Control? The Control is NOT being testedThe Control is used for COMPARISON
14 Other VariablesThe factor that is changed by the experimenter is known as the independent variable.The factor that is being measured or is unknown is called the dependent variable.
15 Example of Controls & Variables For example, suppose you want to figure out if there is a faster route to walk home from school.You will try several different routes beside your regular one and time how long it takes you to get home by each one.Since you are only interested in finding a route that is faster for you, you will do the walking yourself.
16 What are the Variables in Your Experiment? Varying the route is the independent variableThe time it takes is the dependent variableThe control is the regular route.
17 One more thing… it is best to make several trials with each independent variable.
18 Remember: To be a Valid Experiment: Two groups are required --- the control & experimental groupsThere should be only one variable tested at a time
19 Data Results of the experiment May be quantitative (numbers) or qualitative (written observations)
20 Data Must be shared with others. Can be organized into charts, tables, or graphs
21 ConclusionAgrees or disagrees with the hypothesis based on the data obtained from the experiment
22 RetestChange the hypothesis or in order to verify the results, retest the experiment.
24 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