How Scientists Work Section 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