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  1. Notes Scientific Method Chapter 1: Section 2 How Scientists Work

  2. How Scientists Work:Solving the Problems • Much of biology deals with solving problems • These problems can be environmental, ecological, health related, etc. • No matter what types of problemsare being studied, scientists use the same problem-solving steps called… • The Scientific Method

  3. Scientific Method Definition • The scientific method is- • A logical and systematic approach or process to problem solving.  • An organized way of using evidence to learn about the natural world. • According to Wikipedia - Scientific method is a body of techniques for investigating phenomena and acquiring new knowledge, as well as for correcting and integrating previous knowledge. It is based on gathering observable, empirical and measurableevidence subject to specific principles of reasoning, the collection of data through observation and experimentation, and the formulation and testing of hypotheses.

  4. Scientific MethodListing the Steps • Make an Observation • Define the Problem • Research the Problem • State the Hypothesis • Experiment to test Hypothesis • Collect and Record Data • Analyze Data • Draw Conclusions • Determine Limitations • Report Results If needed, Do more investigation

  5. O V E R V I E W • S C I E N T IFIC M E T H O D

  6. Question What does the scientist want to learn more about? First Then Research Gathering of information Scientific Method An Overview Next Hypothesis An “Educated” guess of an answer to the question Then Procedure/ Method Written and carefully followed step-by-step experiment designed to test the hypothesis Next Data Information collected during the experiment And And Observations Written description of what was noticed during the experiment Finally Conclusion Was the hypothesis correct or incorrect?

  7. Question What does the scientist want to learn more about? First Then Research Gathering of information Scientific Method An Overview Next Hypothesis An “Educated” guess of an answer to the question Then Procedure/ Method Written and carefully followed step-by-step experiment designed to test the hypothesis Next Data Information collected during the experiment And And Observations Written description of what was noticed during the experiment Finally Conclusion Was the hypothesis correct or incorrect?

  8. Hypothesis O V E R V I E W Scientific Method Procedures (Experiments) • S C I E N T IFIC Findings (Conclusions) M E T H O D Data (Results) Repeat steps 3-7 for competing hypotheses. Competing hypotheses may include revisions of the original hypothesis suggested by the results of the testing process.

  9. Form a Hypothesis Define / Identify the Problem Make Observations Test Hypothesis Perform Experiments New Experiments Organize and Analyze Data NO Faulty Experiments? Do Experiments and Observations Support Hypothesis? YES Communicate Results Draw Valid Conclusions Here is another example of how the steps may go…. Even though we show the scientific method as a series of steps, keep in mind that new information or thinking might cause a scientist to back up and repeat steps at any point during the process. O V E R V I E W • S C I E N T IFIC M E T H O D

  10. Scientific Method Ask Question • Let’s break each of these steps down into their individual components: Do Background Research Think! Try Again Construct Hypothesis Test with an Experiment Analyze Results Draw Conclusion Hypothesis is True Hypothesis is False or Partially True Report Results

  11. As we all know, frogs have four legs. What’s up with thesefroggies? 1. Observing • Make an observation • See somethingunusual • Frogs withincorrectnumber oflegs!

  12. 2. Questioning • Recognize, state or define the problem • Must be in the form of a question • The obvious question is:  • What is causing these deformities?

  13. 3. Researching • Gather information related to the problem • Read, observe, measure, take samples, etc. • How frogs normally develop from eggs • The % of frogs with the deformities • Number of other species in the pond with deformities • Previous or new pollutantsin the pond • Change in amount of UV (sunlight) exposure on eggs • Etc.

  14. 4. Hypothesizing • A hypothesis is: • An educated guess, trial answer, possible solution, prediction • Must be a statement • Must be testable or measurable • Is based on your research and previous experience

  15. Hypothesizing • List possible explanations (alternative hypotheses) based on your previous experience (what you already know);  and on research you have done   • all of the hypotheses must be testable (no demons allowed!)

  16. Hypothesizing Aliens from outer space- Sorry, this is not allowed because it is not testable using the Scientific Method.  Sheesh! Something Else-Another possibility that we might think of is predation or cannibalism, which seems to be the best explanation for certain kinds of deformities (frogs with missing limbs). If this hypothesis is true, then, at minimum: We should find frogs and/or other pond critters with evidence that their legs have been damaged or bitten off Chemical Pollution-If this hypothesis is true, then: You should be able to find a likely chemical pollutant in the deformed frog ponds You should be able to isolate the chemical from the pond water You should be able to show that the isolated chemical can cause the exact same deformities in the lab These are minimal predictions;  you may have already thought of the fact that chemical pollution should affect all four limbs equally, or that other organisms from the same ponds should show deformities as well Genetic mutation- If this hypothesis is true, then: If we mate deformed frogs the offspring should show similar deformities The deformities should be fairly uniform and predictable The particular deformities should only be found in one species Ultraviolet Radiation-If this hypothesis is true, then: We should be able to measure unusually high levels of UV radiation at deformed frog sites We should be able to use these same levels to induce the exact same kinds of deformities in the lab Can you think of other predictions based on this hypothesis? Disease (virus, parasite, etc.)- If this hypothesis is true, then: We should be able to find the disease-causing agent (for example, parasites) at the deformed frog ponds We should be able to find the parasites in the deformed frogs We should be able to use the same parasite to induce the exact same kinds of deformities in the lab Loud Rock + Roll Music-Okay, this is testable, but WHY test it??? (get real) • Some possible explanations (hypotheses) for the frog deformities: Genetic mutation Chemical Pollution Ultraviolet Radiation Disease (virus or parasite or...?) Loud Rock & Roll Music Aliens from outer space Something else

  17. 5. Experimenting • Testing the hypothesis • Pick the hypothesis that makes the most sense and is easy to test • Then design a controlled experiment

  18. Experimenting • Go to the web site for Hartwick College to see the experiments and how the scientific method was actually used to find out the cause of recently found frog deformities. • http://www.hartwick.edu/biology/def_frogs/Introduction/Exploration/explore.html

  19. Experimenting • Let’s look at the text book example of the Scientific Method using Redi’s Experiment on Spontaneous Generation • He was trying to disprove the idea of SpontaneousGeneration (or actually that flies came frommaggots, which camefrom flies) Francesco Redi (1668)

  20. Stating the Problem • Example: How do new living things come into being? • Spontaneous generation once commonly accepted • Redi wanted to show what caused the appearance of maggots (and then flies) on meat

  21. Belief based on prior observations • If leaf lands on water it becomes a fish • If bale of hay left in barn it produces mice • Muddy soil gives rise to frogs • Meat hung out in the market is the source of flies

  22. Belief based on prior observations • Redi observed that maggots appeared on meat a few days after flies were on meat • No microscope = no way to see eggs • But Redi believed that maggots came from eggs that were laid by flies

  23. Forming a Hypothesis Redi’s Hypothesis: Flies produce maggots. • How could he test this? • Through a controlled experiment

  24. Jars with meat Uncovered jars Covered jars Redi’s Controlled Experiment • Redi used two groups of jars • Jars that contained meat and no cover • Jars that contained meat and gauze cover

  25. Uncovered jars Two groups of jars Covered jars Control and Experimental Groups Control group: • used as a standard of comparison • the group containing the factor (variable) that has been changed Experimental group: (manipulated or independent variable)

  26. Variables in an Experiment • Variables - Factors that can be changed • Controlled Variables - all the variables that remain constant • Manipulated Variable - (also called the Independent Variable) - factor in an experiment that a scientist purposely changes • Responding Variable- (also called the Dependent Variable) - the outcome or results, factor in an experiment that may change because of the manipulated variable….what a scientist wants to observe

  27. Setting up a Controlled Experiment • In a controlled experiment, only one factor is changed at a time. • Independent variable: the factor that is deliberately changed • Dependent variable: the factor that the scientist wants to observe; it changes in response to the independent variable

  28. Variables in Redi’s Experiment • Controlled Variables: jars, type of meat, location, temperature, time • Manipulated Variables: gauze covering that keeps flies away from meat

  29. Two groups of Jars with meat Uncovered jars Covered jars Let’s think about this.… Uncovered jars • Which is the control group? • Which is the experimental group? Covered jars

  30. Redi’s Experiment on Spontaneous Generation OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat. HYPOTHESIS: Flies produce maggots. PROCEDURE Covered jars Uncoveredjars Controlled Variables: jars, type of meat, location, temperature, time Several days pass Manipulated Variables: gauze covering that keeps flies away from meat Responding Variable: whether maggots appear Maggots appear No maggots appear CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.

  31. 6. Collect and Record Data Data: observations and measurementsmade in an experiment Types of Recorded Data • Quantitative - observations that involve measurements/numbers; i.e. 3 days, 12 maggots, 4 g, 13 sec, 8 liters • Qualitative - observations thatdo not involve numbers, are of a descriptive naturei.e. white maggots covered the meat, leaves were all wilting

  32. 7. Analyze the Data • Examine data tables, charts, and graphs • Examine experimental notes • Look for trends, patterns, and averages • What does the data show • Put your data into words

  33. 8. Draw Conclusions • Restate the hypothesis: Example: Flies produce maggots. • Accept or reject the hypothesis. • Support your conclusion with specific, numerical data. • What was Redi’s conclusion? • Flies lay eggs too small to be seen. • Maggots found on rotting meat are produced from the eggs laid by flies. • Maggots are not appearing due to spontaneous generation!

  34. 9. Determine Limitations • Scientists look for possible flaws in their research • They look for faulty (inaccurate) data • They look for experimental error or bias's • They decide on the validity of their results • They make suggestions for improvement or raise new questions

  35. 10. Publish Results • Communication is an essential part of science • Scientists report their results in journals, on the internet, or at conferences • This allows their experiments to be evaluated and repeated • Scientists can build on previous work of other scientists Redi’s experiment on insects generation

  36. Repeating the Investigation • Sometimes results are unexpected. • John Needham challenged Redi’s experiment and designed his own to show that spontaneous generation CAN occur under certain circumstances. • Lazzaro Spallanzini designed a slightly different experiment to improve on Needham’s work Repeat the experiment!

  37. Repeating the Experiment(continued) • Louis Pasteur further modified the experiment.

  38. Scientific Method How Scientists Work Solving the Problems The reason scientific work is called “RE-search” rather than just "search " is because it is an ongoing process that often times changes our view of the natural world.It is subject to modification in light of new evidence and new ways of thinking.

  39. S C I E N T IFIC M E T H O D R E V I E W

  40. Define the Problem Report Results Analyze Data Make an Observation State the Hypothesis the Problem Can you put these steps in order? 10 8 2 7 6 4 3 1 9 5 Determine Limitations

  41. Define the Problem Report Results Analyze Data Make an Observation State the Hypothesis the Problem Steps of ScientificMethod in order 1 4 2 5 3 8 7 9 6 10 Determine Limitations

  42. Scientific Theory • A theory is an explanation of a set of related observations or events based upon proven hypotheses and verified multiple times by detached groups of researchers

  43. Scientific Law Scientific Method • Scientific laws represent the cornerstoneof scientific discovery • They must be simple, true, universal, and absolute • If a law ever did not apply, then all science based upon that law would collapse