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Scientific Method

Scientific Method. How to Perform Investigations. Scientific Methods. Scientific methods are common steps used by scientists to gather information and answer questions Steps of scientific method can vary but generally are the following:. 1. Observations. 5. Forming a theory.

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Scientific Method

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  1. Scientific Method How to Perform Investigations

  2. Scientific Methods • Scientific methods are common steps used by scientists to gather information and answer questions • Steps of scientific method can vary but generally are the following: 1. Observations 5. Forming a theory 2. Making a hypothesis 6. Develop new hypothesis 3. Collecting Data 4. Publishing results

  3. Observations • Making observation(act of recognizing and noting a fact or occurrence) about something that no one has noticed before • Ex: notice that certain soybean plants are growing taller than normal and also see mushrooms (fungus) in soil near their roots • other soybean plants are normal height and they don’t have any mushrooms in the soil • Hmmmm….

  4. Soybean Plants - Make soybeans (AKA edamame) Fungus (mushrooms)

  5. Making a Hypothesis • A hypothesis is a testable answer to a question • Hypothesis: a logical (using reason) explanation for a question or a problem that can be tested; much like a prediction • explanation may be proved wrong, but it could be right! • Ex: “The presence of fungus in the soybean plant’s soil increases its growth rate” = +

  6. Collecting Data • In order to test a hypothesis one must conduct an experiment • Experiment: a procedure that tests a hypothesis by the process of collecting data (information) • Sometimes might make separate “experiment” category in “scientific method” lists • data collected can prove or disprove a hypothesis

  7. Experiments… • Experiments involve two distinct groups: • Control group: group in which all conditions are kept same (normal) • Need only one control group in the experiment. • Experimental group: group in which all conditions are kept same except for one single condition being tested • May have as many as can be observed.

  8. Which is our control group and which is our experimental group? Control: soybean plants without fungus in soil Experimental: soybean plants with fungus in soil + Single condition

  9. Each experiment must have certain variables otherwise experiment is worthless • Independent variable: condition that is changed in an experiment (the one single condition) • Ex: fungus (we added it to the soil in experiment) • Dependent variable: condition that results from changes made to the experiment • Ex: growth rate of soybean plants (height of plants) + vs.

  10. Data is based on facts, not assumptions! • Fact: something that has actual existence; can be proven to be true • “School on a normal day at Cleveland HS starts at 7:57 am.” • Assumption: a notion taken for granted, usually based on some factual evidence • “At Nobel MS, we got out early every Tuesday so it’s the same at Cleveland HS.”

  11. Collected data is analyzed and one comes up with a conclusion by deduction (deriving of a conclusion by reasoning) • yes, adding fungus to soil makes soybean plants grow taller • great, you made a discovery! • no, adding fungus to soil does not make a difference in growth of soybean plants • great, now you know what NOT to focus on next time. The plants STILL are growing taller than normal, so something MUST be triggering that

  12. Data falls into two categories: • Qualitative - data that deals with descriptions of evidence (words); can be observed, not measured • “These soy plants are tall. Those soy plants are short.” • “The soy plant flowers are pink. The pods are wrinkled.” • Quantitative – data that deals with numerical evidence; can be measured • “These soy plants averaged 6.5 cm tall. Those soy plants averaged 11 cm tall.” • “750 or 66% of soy plant flowers are pink. 250 or 25% of the pods are wrinkled.”

  13. Publishing Results • Results of an experiment are useful only if they are made available to other scientists so they can verify results • If no one knows about it, no one can prove or disprove it • Unless another scientist can reproduce the experiment with the same results, may become an inference (act of passing statistical sample data as general conclusion) that may be incorrect • Anti-wrinkle creams • Weight loss drugs • Anti-aging pills

  14. Why is Publication Necessary? • Which European is credited with “discovering” North America? • Christopher Columbus • Which European peoples really “discovered” North America? • Vikings • Why did Columbus get the credit? • Columbus told everyone who would listen, whereas the Vikings kept it secret

  15. Forming a Theory • A theory is a hypothesis that is supported by a large (humungous) body of scientific evidence • only after evidence is collected, tested by different individuals many times, and published can a hypothesis become a theory THEORY HYPOTHESIS

  16. Hypothesis vs. Theory vs. Law • What’s the difference between a hypothesis, a theory, and a scientific law? • hypothesis: statement that has no proof • “I am the best teacher at Cleveland High School.” • theory: hypothesis that is proven correct • “Smoking Causes Lung Cancer, Heart Disease, Emphysema, And May Complicate Pregnancy.” • scientific law: true and universal fact • “What goes up, must come down.”

  17. Developing New Hypothesis • New theory may prompt scientists to ask new questions or form additional hypotheses Ex: If smoking causes lung cancer, what exactly in cigarettes causes it? Tar? Nicotine? Additives? • A new hypothesis means there must be a new experiments and publishing • New hypothesis: Tar in cigarettes causes lung cancer. • Theories are revised as new information is gathered

  18. END • Test on Scientific Method Thursday 8/22!

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