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 affect 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 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.
16 What are the Variables in Your Experiment? Varying the route is the independent variableThe time it takes is the dependent variableKeeping the same walker throughout makes the walker a control variable.
17 One more thing… it is best to make several trials with each independent variable.
19 Remember: To be a Valid Experiment: Two groups are required --- the control & experimental groupsThere should be only one variable
20 Data Results of the experiment May be quantitative (numbers) or qualitative (words)
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.
24 Recap: To Solve a Problem 1)Identify a Problem2) 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
25 No need to write these slides down in notebook Review…No need to write these slides down in notebook
26 In what part of the scientific method do you write an investigative question? Identify the problem
27 What are the two parts of the analysis? Create a graph and write a summary
28 A conclusion needs to support or repudiate your _____________. hypothesis
29 How do we record data in an experiment? data tables (rows and columns)
30 The independent variable may change the ________ variable in an experiment.
31 When we are finished with our experiments we ____________ our findings. communicate
32 What do we call information collected during the experiment? Data
33 The procedure is a list of__________ that describes the experiment. Steps
34 How many times should an experiment be repeated? Many times to help average issues such as human error
35 Variables that are kept the same are called ___________ controls