The document discusses the scientific method and key aspects of experimental design in science. It defines science as using an evidence-based process to explore and explain the natural world. The scientific method involves making observations, asking questions, developing hypotheses, conducting experiments to test predictions, and analyzing results. Well-tested hypotheses that withstand rigorous scrutiny may become accepted scientific theories. Controlled experiments are described as a key way to test hypotheses by systematically manipulating variables while holding all other factors constant.

1. SCIENCE

2. Definition of Science A way of exploring and explaining the natural world Using a process designed to reduce the chance of being misled

3. SCIENTIFIC METHOD PART I :

4. The Scientific Method Make observations Ask questions Develop a hypothesis Make predictions Test the predictions Experiment Manipulate variables Independent Dependent Conclusions: analyze and interpret results Peer Review/Publication The “scientific method” is a formalized version of the procedure any of us might take, using common sense, to resolve a problem. (Withgott and Brennan, 2007)

5. 1. OBSERVATION The light doesn’t turn on

6. 2. QUESTION Why didn’t the light turn on?

7. 3. MULTIPLE HYPOTHESES What are all the possible answers (hypotheses) to the question? Example: The light bulb is burned out Example 2: ?

8. 4. PREDICTIONS What data would support a particular hypothesis (= expected data) and/or what data would refute the hypothesis? Example: The light bulb will rattle when shaken

9. 5. TESTS (Experiments) Conduct tests to collect actual data? Example: Shake the light bulb and record sound

10. 6. TENTATIVE CONCLUSIONS Which hypotheses were supported (not refuted) by the actual data? Write up report (introduction, methods, results, discussion) for publication

11. 7. PEER REVIEW & PUBLICATION Submit your report to a scientific journal that is peer-reviewed, meaning that your methods, data, tentative conclusions will be scrutinized by scientists whose reputation is at stake if they allow your report to be published. Publication leads to creation of scientific information

12. The Scientific Method Scientific understanding advances through evaluation and dissemination of information to the scientific community. How does this information get disseminated to the public? (Withgott and Brennan, 2007)

13. THE NATURE OF SCIENTIFIC PROOF & KNOWLEDGE PART II:

14. Nature of scientific proof Hypothesis: A possible explanation or statement that might be true and will be tested by the scientific method. Can be falsified Cannot be positively proven Therefore, hypothesis are accepted not proven

15. Nature of scientific proof Example: Observation: All the swans you have ever seen are white Hypothesis: All swans are white Test: examine large number of swans Tentative conclusion: all swans are white (hypothesis accepted) If you looked at a million white swans, there could still be a black one However, if you found just one black swan, your hypothesis would be falsified

16. Nature of scientific proof When a hypothesis withstands RIGOROUS testing, especially over time, it becomes a theory Theory: A hypothesis that has been rigorously tested and over time has become generally accepted by the scientific community as correct

17. Nature of Scientific Proof Some examples of theories are: Theory of relativity Theory of plate tectonics Theory of evolution Eventually theories become laws Law of gravity

18. Nature of Scientific Knowledge The main body of science is very stable and grows by being corrected slowly So, although scientists accept that scientific knowledge is always open to improvement, the main body of knowledge is well-accepted and stable

19. Scientific Worldview There are several beliefs underlying the work of scientists: By working together over time, people can figure out how the world works Knowledge is both stable and changing Scientists become excited by new ideas, but are skeptics that judge ideas by the strength of the evidence that supports them.

20. Scientific Worldview The universe is a unified system functions in accordance with fixed natural laws that do not change from time to time or from place to place Knowledge gained from studying one part of it can often be applied to other parts of it All events arise from some cause or causes and, in turn, cause other events. We can use our senses and reasoning abilities to detect and describe natural laws that underlie the cause and effect relationships we observe in nature.

21. Are the terms Science and Technology synonymous?

22. Science  Technology Technology = the application of scientific knowledge for practical purposes.

23. EXPERIMENTAL DESIGN PART III:

24. Experiments--definition A way to test an hypothesis

25. Experiments—some rules Adequate Sample Size. Ex. Larger sample size better Representative Sample. Ex. Random sample

26. Experiment—different types Observational experiment Manipulative approach (or controlled study) Natural experiment Theoretical experiment .

27. Observational Experiment Systematic study of natural variation Searches for correlation or statistical association among variables Examples: Measuring patterns of species diversity across the continent Do the number of herbivores increase with increased plant numbers & productivity Challenge: Hard to control variables Hard to determine cause & effect Benefits: Can be done over large areas of space & time

28. Manipulative or controlled study Uses a model system to control and manipulate variables An experiment in which variables are taken into account Based on comparing a control group with an experimental group Both groups are treated identically except for one variable or factor This factor is changed for the experimental group but not the control group If an effect is seen in the experimental group but not the control group that indicates that the factor changed is the cause of the effect

29. Examples of Controlled Studies Studying the effect of nutrients on plant growth—add or change the kinds & amounts of nutrients in natural or artificial setting Studying the effect of grazing on plant communities—exclude grazing on study plots & allow grazing on others Challenge: hard to do over large scales of space & time

30. Manipulative or controlled study Variables : factors that affect observations or experiments Dependent variable—response that is measured Independent variable—varied or manipulated by researcher (cause)

31. Natural Experiment Similar to manipulative study except that manipulations are caused by natural event such as: Volcanic eruption Flash flood Fire Pest outbreak Challenges: hard to control all variables & to know when natural events will occur Benefits: studying natural events

32. Theoretical Experiment Uses logic and mathematical proofs to develop general principles for making and testing predictions

33. AN EXAMPLE OF A MANIPULATIVE OR CONTROLLED STUDY THE MEALWORM MYSTERY

34. MEALWORM MYSTERY A student conducted 4 experiments to determine how mealworms respond to light and moisture. All variables except light and moisture were held constant from experiment to experiment. For each experiment, 12 mealworms were placed in the center of a box and then their positions were recorded 24 hours later .

35. EXPERIMENT 1 QUESTION : Are mealworms attracted to light? mealworm QUESTION 2 : Are mealworms affected by moisture? Answer? You can’t tell; it could be either or both

36. EXPERIMENT 2 QUESTION : Are mealworms affected by light? QUESTION 2 : Are mealworms affected by moisture? Answers? They are affected by light; we don’t know about moisture

37. EXPERIMENT 3 QUESTION : Are mealworms affected by light? QUESTION 2 : Are mealworms affected by moisture? Answers? With just this experiment, it seems they didn’t move

38. EXPERIMENT 3 QUESTION : Are mealworms affected by light? QUESTION 2 : Are mealworms affected by moisture? Using the information from the other 2 experiments… Answers? Yes and Yes (despite attraction to light, they avoided wet

39. THE EXPERIMENTS 1 2 3 QUESTION: Which variables affect mealworm movement based on the above experiments (note that movement may be either toward or away from something)? A . Light but not moisture. B . Moisture but not light. C . Both light and moisture. D . Neither light nor moisture. E . Can’t tell. mealworm Without the controlled experiment we would know nothing!