Scientific Method

1. Scientific Method YAY!!!!

2. Steps in the Scientific Method • Observation • Hypothesis • Experiment • Data Collection • Conclusion • Retest

3. Observations • Gathered through your senses. • A scientist notices something in the natural world. • Repeated observations over a long period of time.

4. Observations • An example of an observation might be that young dolphins and small porpoises with horrific injuries continually show up on the shores of Virginia and Scottland’s East coast.

5. Hypothesis • A suggested solution to a problem. • Must be testable. • Written as an “If…then…” statement. • Predicts an outcome.

6. Hypothesis • A hypothesis might be that the mammals had died through 'blast trauma'. In American cases, this was supposedly from exercises by the US Navy, and in Scotland from air guns used by oil rig technicians to detect undersea caverns.

7. Experiment The hypothesis was dismissed after further examination of the mammals' bodies revealed the injuries - broken ribs, imploding lungs, damaged livers and massive internal bleeding - could only have come from prolonged, focused attacks. When tell-tale teeth-marks were identified, the dolphin - the mammal classified as one of the world's most intelligent, sensitive and sociable creatures - became the official suspect. Confirmation of the murders came by way of two shocking films shot by holidaymakers. • A procedure to test the hypothesis. • Can be an experiment, model, or observation.

8. A Good Experiment • Will be repeatable. • Change only one variable at a time. • Will have a large sample size.

9. Variables, Controls, and Constants

10. Scientific Experiments Follow Rules • An experimenter changes one factor and observes or measures what happens.

11. Variables • Variable • Factor in the experiment that is being tested.

12. Independent Variable • The factor that is changed by the experimenter is known as the independent variable. • Its effects are measured by changes in the dependent variable • It will be graphed on the X-AXIS

13. Dependent Variable • The factor that is measured or observed is called the dependent variable. • Observed and measured during the experiment • Graphed on the Y-AXIS

14. Graphing Variables • The independent variable would be the temperature. • The dependent variable is the metabolic rate.

15. Constants Susie want to know how different colors of light effect the growth of plants. She buys 5 ferns of the same species, which are all approximately the same age and height. She places one in white light, one in blue light, one in green light, one in red light, and one in a closet. All of the ferns are planted in Miracle Grow and given 20 mL of water a day for two weeks. After the two weeks, Susie observes the plants and takes measurements. • The experimenter makes a special effort to keep other factors constant so that they will not effect the outcome. In this experiment, the species, age, original height, the soil and amount of water are ALL constants.

16. Controls • Establish a “status quo” • How conditions are under normal circumstances. • Controls are NOT being tested. • Controls are used for COMPARISON

17. Example… • Susie want to know how different colors of light effect the growth of plants. She buys 5 ferns of the same species, which are all approximately the same age and height. She places one in white light, one in blue light, one in green light, one in red light, and one in a closet. All of the ferns are planted in Miracle Grow and given 20 mL of water a day for two weeks. After the two weeks, Susie observes the plants and takes measurements.

18. Variables in this experiment… • Variations in the light color are the independent variables • Growth in the plants are the dependent variables • Having the same species at the same age, starting out at the same height, using the same soil and amount of water are all constants. • The plant that was placed in the closet is the control.

19. Why do scientists repeat experiments? • In order to verify results, experiments must be RETESTED! • It adds validity to the findings.

20. Valid Experiments • Two groups are required --- the control & experimental groups • There should be only one variable each experiment

21. Data • Results of the experiment • May be quantitative (numbers) or qualitative (descriptive)

22. Data • Must be organized • Can be organized into charts, tables, or graphs

23. Trends in Data • Negative (inverse) • When one increases, the other decreases • Positive (direct) • When one increases, the other increases OR when one decreases, the other decreases • No relationship • One has NO EFFECT on the other.

24. Conclusion • The answer to the hypothesis based on the data obtained from the experiment

25. How do scientists communicate findings? • When scientists want to communicate the results of their experiment, they use SCIENTIFIC JOURNALS or other publications!

26. Pure and Applied Science • Pure Science • Answers questions about phenomena and mechanisms in the natural world. • Why do you do it? • Because we wanted to know! • EX. Studying the dolphin deaths • Applied Science • Application of scientific knowledge to practical problems. • Why do you do it? • To fight disease, identify criminals, learn how to store hazardous wastes…etc.