Scientific Method

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

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