(an intro to AP Biology)

Transcription

1 (an intro to AP Biology)

2 1. How does being science literate benefit you and your community? 2. What is the most critical element in the process of doing science? 3. What is meant by the phrase the fuel on which science runs is ignorance and mystery. 4. Why is it important to have so much emphasis on the scientific method?

3 Gullible? Skeptical?

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7 2 lists: What science IS What science IS NOT BRAINSTORM

8 BASED ON PROOF RIGID BASED ON BELIEF BASED ON FAITH BASED ON AUTHORITY DECIDED BY DEBATE OR LAW A SEARCH FOR TRUTH CERTAIN FAIR ABLE TO SOLVE ALL PROBLEMS A COLLECTION OF FACTS DEMOCRATIC ABSOLUTE

9 Science IS: LIMITED TO THE NATURAL WORLD OBSERVABLE TESTABLE MEASURABLE REPEATABLE MODIFIABLE VERIFIABLE BUILT UPON TESTABLE PREDICTIONS BASED ON EXPERIMENTATION OPEN TO CHANGE BIASED DISPROVABLE OBJECTIVE STRONG THEORIES INFERRED FROM SOLID EVIDENCE MADE STRONGER BY DIFFERENT LINES OF EVIDENCE A SEARCH FOR UNDERSTANDING

10 Scientific knowledge is durable but tentative. Scientific activity requires both being logical/systematic and creative/imaginative. Because of social, historical and cultural influences, science can be subjective and have bias. Science and its methods cannot answer all questions. There is no such thing as a single scientific method.

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12 Theories* are the ultimate goal of science. They explain observations and are tested by generating hypotheses. These three things are distinct aspects of science. *as opposed to proof or truth

13 How do we know? Why do we Believe it? What s the Evidence?

14 How do we go about studying science? We need an organized way to generate reliable data and relate the data concepts, relationships, etc.

15 Applying the Scientific Method

16 The Scientific Method ** A systematic method to understand the natural world with reference to natural laws.**

17 Scientific method 1. Ask a Question 2. Do some background research. 3. Form a testable hypothesis 4. Experiment 5. Analyze results. 6. Draw Conclusions

18 Too often the scientific method is presented in schools and textbooks as a "recipe" for doing science, with numbered steps even! That's misleading. Science progresses through trial and error, mostly error. Every new theory or law must be skeptically and rigorously tested before acceptance. Excerpts from his Internet article

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22 From A Detailed Examination of Scientific method, Craig Rusbult

23 The most reliable means to ensure that experiments produce reliable information in response to a specific question. The steps taken to answer a specific question.

24 Scientific method is based on the principle of cause and effect: You get a fever because you are sick; the sky looks blue because of the interaction of light and matter in the atmosphere. Not all common phenomena are completely understood, and still others cannot be explained at all so far

25 A general pathway Observe world (collect observations/facts) Ask why questions. Make explanatory hypothesis Make predictions or retrodictions. Test these by experiment or further observation (assume uniform cause and effect) Eventually form a theory.

26 Design a testable experiment based on a prediction (hypothesis). Have you identified WHAT kind of data you need in order to answer the question? Have you designed a protocol that will generated the type of data you need to answer the question? (your independent/manipulated variable) Have you controlled for as many variables as possible so your results reflect your targeted dependent (responding) variable?

27 the thinking used in science is not strange and mysterious, it's the same thinking you use in daily life. In scientific logic, as in daily life, you use reality checks to decide whether "the way you think the world is" matches "the way the world really is." the central activity of modern scientific method, when OBSERVATIONS (from an Experiment) and PREDICTIONS are compared in a REALITY CHECK that is a test of quality for a Theory From A Detailed Examination of Scientific method, Craig Rusbult

28 These are not the same when evaluating the results of an experiment. Analysis - describes and discusses the results what happened and why? Conclusion relates the results and analysis to the original problem and proposes a theory (resolution) based on the analysis How does this provide an answer to the question?

29 A well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses. (NAS, 1998) Science not only generates facts, but seeks to explain them, and the interlocking and wellsupported explanations for those facts are known as theories. (T. Ryan Gregory, 2008)

30 Theories attempt to answer the original question/problem, and are a supported by evidence from the results of experimentation.

31 An idea, model, or explanation that has been rigorously tested, analyzed, and accepted by the scientific community - a term used, perhaps, because nothing can ever be proved absolutely true. The theory will continue to be an accepted explanation unless new information is uncovered - information that disproves the previous explanation.

32 no matter the specific pathway all science processes which attempt to explain a natural phenomenon start with

33 Science can only deal with things that can be OBSERVED. Good Science = Good Observations

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37 The elements of a controlled experiment.

38 1. Make an observation 2. Speculate (ask a question) 3. Form a hypothesis to answer the question 4. Make a prediction (what else would be true if your hypothesis is correct?) 5. Test it generate quantifiable data Use statistical tests to evaluate Life, pg. 13

39 1. observation: decreased amphibian pop. world wide 2. Speculate: what is the cause? 3. Hypothesis: (several) exposure to atrazine 4. Prediction : frog tadpoles exposed to atrazine would show adverse effects at adulthood 5. Test it: controlled and comparative studies

40 controlled Manipulates one or more factors being tested. Predicts that some variable has an effect. Devise a method to manipulate only that variable (experimental group). Compare data with data from unmanipulated (control) group. comparative Compare unmanipulated data from different sources. Assumes there are differences between groups or samples. Cannot control variables. Gather and compare data. Apply statistical analysis to determine if the manipulated variable created the difference (as opposed to random chance). Figs & 1.14 pgs. 15,16

41 One variable is manipulated (IV) while the others are held constant. Independent Variable (IV) The independent variable is what is controlled (selected and/or changed) by the experimenter. It is selected to determine its relationship to an observed phenomenon (i.e., the dependent variable). Dependent Variable (DV) The dependent variable is the event studied and expected to change. It is the response that is measured. The dependent variable, usually cannot be directly controlled.

42 Can you identify them? An experimenter wishes to measure the degree to which caffeine intake influences explicit recall for a word list. caffeine intake recall for a word list independent variable dependent variable

43 An Experimental Control (control group) is used as a constant to which the data can be compared. You can t tell if something has changed if you don t identify a starting point. Controlled variables are the variables that are kept constant to prevent their influence on the effect of the independent variable on the dependent.

44 Smithers thinks that a special juice will increase the productivity of workers. He creates two groups of 50 workers each and assigns each group the same task (in this case, they're supposed to staple a set of papers). Group A is given the special juice to drink while they work. Group B is not given the special juice. After an hour, Smithers counts how many stacks of papers each group has made. Group A made 1,587 stacks, Group B made 2,113 stacks. Identify the: 1. Control Group 2. Independent Variable 3. Dependent Variable 4. What should Smithers' conclusion be? 5. How could this experiment be improved?

45 Homer notices that his shower is covered in a strange green slime. His friend Barney tells him that coconut juice will get rid of the green slime. Homer decides to check this this out by spraying half of the shower with coconut juice. He sprays the other half of the shower with water. After 3 days of "treatment" there is no change in the appearance of the green slime on either side of the shower. Identify the: 2. Experimental Control 3. Independent Variable 4. Dependent Variable 5. What should Homer's conclusion be?

46 Bart believes that mice exposed to radio waves will become extra strong (maybe he's been reading too much Radioactive Man). He decides to perform this experiment by placing 10 mice near a radio for 5 hours. He compared these 10 mice to another 10 mice that had not been exposed. His test consisted of a heavy block of wood that blocked the mouse food. he found that 8 out of 10 of the radio-waved mice were able to push the block away. 7 out of 10 of the other mice were able to do the same. Identify the- Control Group Independent Variable Dependent Variable What should Bart's conclusion be? How could Bart's experiment be improved?

47 Krusty was told that a certain itching powder was the newest best thing on the market, it even claims to cause 50% longer lasting itches. Interested in this product, he buys the itching powder and compares it to his usual product. One test subject (A) is sprinkled with the original itching powder, and another test subject (B) was sprinkled with the Experimental itching powder. Subject A reported having itches for 30 minutes. Subject B reported to have itches for 45 minutes. Identify the- Control Group Independent Variable Dependent Variable Explain whether the data supports the advertisements claims about its product.

48 Lisa is working on a science project. Her task is to answer the question: "Does Rogooti (which is a commercial hair product) affect the speed of hair growth". Her family is willing to volunteer for the experiment. Describe how Lisa would perform this experiment. Identify the control group, and the independent and dependent variables in your description.

49 In summary: Independent variables (I vary) answer the question "What do I change? Dependent variables answer the question "What am I going to observe or measure? Controlled variables answer the question "What do I keep the same? The Experimental Control answers the question How do my results compare?

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