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How Scientists WorkSection 1-2 Experimenting - Conducting scientific investigations systematically, including identifying and framing the question carefully, forming a hypothesis, managing variables effectively, developing a logical experimental procedure, recording and analyzing data, and presenting conclusions based on investigation and previous research.
Designing an Experiment • In this class, you will be asked to analyze the experiments of others, as well as to design and carry out your own experiments. • That makes this section very important!!
Designing an Experiment • OBSERVE!!! • Asking a Question • Forming a hypothesis – 2 types: • If (this happens) , then this (these) will be the result(s) , because (scientific explanation based on prior knowledge or experience) . • Null hypothesis: states that there will be NO DIFFERENCE in the two experimental designs. • Setting up a CONTROLLED experiment • Recording and analyzing results • Drawing a conclusion
6. Setting up a CONTROLLED experiment • Variable: a factor in an experiment that can change • Ideally, only ONE variable changes at a time. WHY??? • What do we called variables that are not allowed to change? Controlled variables • Controlled experiment: one in which only one variable is allowed to change (be tested) at a time: • Manipulated variable: AKA, independent variable • Responding variable: AKA, dependent variable
Francesco Redi’s Experiment on Spontaneous Generation (1668)
John Needham (1745) and Lazzaro Spallanzani’s Tests of Redi’s Findings
Louis Pasteur’s (1864) Test of Spontaneous Generation • http://bcs.whfreeman.com/thelifewire/content/chp03/0302003.html • What other important discoveries are credited to Louis Pasteur? • In each of these instances, Pasteur observed a problem, and sought to design experiments to address the questions asked.
Theory • “What’s wrong with my car?” “Well, my theory is……….” What is wrong with this statement????? • Theory: “a well-tested explanation that unifies a broad range of observations” • Could the above statement be correct? • Can a theory be considered the absolute truth? • Law of gravity vs. germ theory of disease
Assignment • Analyzing Data (p.27) ---- Answer in complete sentences!!!! • Images from https://yhs-raines.wikispaces.com/Life+Unit