The Scientific Method*Making observationsAsking questionsDeveloping a hypothesisDesigning an experimentCollecting dataMaking inferencesResults (peer review)
Experimental Design*Experiment: def. – an investigation
consisting of procedures that tests a hypothesis by collecting data under controlled conditions.
InvestigationProceduresControlled conditions
Control vs. Experimental Group*Control: def – the standard in which
all conditions in the experiment are kept the SAME
*Experimental (test) group: def – all conditions are kept the same except for the condition in question being tested
Why do we need both groups?
Flaming Dollar RevisitedQuestion: What is the effect of the
amount of isopropyl alcohol on the dollar bill’s burning intensity?
What is the Control Group?What is the Experimental Group?
Flaming Dollar Control Group(Control: def – the standard in which
all conditions in the experiment are kept the SAME)
Control group – soak the dollar bill in ONLY WATER. (NO ALCOHOL IN SOLUTION)
Flaming Dollar Experimental Group(Experimental group: def – all
conditions are kept the same except for the condition in question being tested)
Experimental group – soak the dollar bill in varying concentrations of isopropyl alcohol. (testing the effect of amount of alcohol)
Variables*Independent variable: def – the one condition that is tested because it affects the outcome of the experiment
*Dependent variable: def – the observable condition that “depends” on changes made to the independent variable
Flaming Dollar RevisitedQuestion: What is the effect of the
amount of isopropyl alcohol on the dollar bill’s burning intensity?
What is the Independent Variable?What is the Dependent Variable?
Flaming Dollar Independent Variable(Independent variable: def – the one
condition that is tested because it affects the outcome of the experiment)
Independent variable – the amount (concentration) of alcohol used in solution to soak the dollar bill
Flaming Dollar Dependent Variable(Dependent variable: def – the
observable condition that “depends” on changes made to the independent variable)
Dependent variable – the burning intensity that depends on the different amounts of alcohol used.
FINAL THOUGHT!*ONLY TEST ONE variable at a time!!!
Example: Flaming DollarAmount of alcohol usedDifferent $ bill amounts used
MUST TEST SEPARATELY!!!