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The Scientific Method. There is simply no fixed set of steps that scientists always follow, no one path that leads them unerringly to scientific knowledge. “The Scientific Method”. Question or Problem 2) Hypothesize Predict Consequences 4) Experiment 5) Interpret Experimental Results.
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The Scientific Method • There is simply no fixed set of steps that scientists always follow, no one path that leads them unerringly to scientific knowledge.
“The Scientific Method” • Question or Problem 2) Hypothesize • Predict Consequences 4) Experiment • 5) Interpret Experimental Results
Experiments • An experiment is a test used to determine if there is evidence to support a hypothesis
What is a hypothesis? • A hypothesis is a guess or prediction about a phenomenon. • Hypotheses can be stated as positive or negative. • The “null” hypothesis predicts that there will be NO difference between experimental groups.
Write your own hypothesis • Write your prediction for the outcome of the radish seed experiment • You should also provide a REASON. • Why do you think the experiment will turn out the way it will?
What is a theory? • A theory is an explanation that has a very large amount of evidence to support it. • A fact is an observation about nature. A theory is an explanation. So a theory can never “become” a fact.
Experiment Titles • Usually, experiments are titled in a format like this: • “The Effect of _______ on _________” • Sample title: “The Effect of Light on Growth of Radish seeds”
Experimental variables • The ONE factor that you cause to be different between experimental groups is the MANIPULATED variable (also called INDEPENDENT variable). • Sample: In the radish seed experiment, the manipulated variable is”Amount of Light”
Experimental variables • The factor that you measure as the outcome of the experiment is called the RESPONDING variable (also called DEPENDENT variable) • In the radish seed experiment, the responding variable is ___________. • The responding variable is LENGTH of STEM, measured in millimeters.
Constants • All other factors in the experiment must be controlled so they are the same for all groups. • Examples of constants in radish seed experiment: • Type of Petri dish type of seed • Number of seed paper towel • Water, Location temperature
Measurements • Obtain a flexible plastic ruler and measure the length of the radish seeds today in millimeters. • Record your data and your partner’s data in the data table.
Observing plant growth: • Take bean and pea seeds and put them in containers of soil under our light source. • Water them consistently. • Each day in class, take note of any changes that you observe.
Measure the responding variable • Draw a data table for recording radish plant sizes Growth (mm) in Light Growth (mm) in Dark Date
Writing an experiment description • Title • Hypothesis • Short description of procedure • Identify control and experimental groups. • Name the manipulated, responding variables • Identify five constants