1 Chapter 1: Section 2 How Scientists WorkNotes Scientific Method Chapter 1: Section 2 How Scientists Work

2 Lecture Outline – The Scientific MethodPowerPoint Notes textbook questions Keys

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

4 Scientific Method DefinitionThe 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.

5 Scientific Method Listing the StepsMake 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

6 S C I E N T I F I C O V E R I W M E T H O D

7 Scientific Method An Overview Question Research Hypothesis Procedure/First What does the scientist want to learn more about? 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 Scientific Method An Overview Question Research Hypothesis Procedure/First What does the scientist want to learn more about? 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?

9 Procedures Findings DataHypothesis S C I E N T I F I C O V E R I W Scientific Method (Experiments) Procedures (Conclusions) Findings 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.

10 S C I E N T I F I C O V E R I W M E T H O DForm a Hypothesis Make Observations Define / Identify the Problem Test Hypothesis Perform Experiments New Experiments Do Experiments and Observations Support Hypothesis? YES Organize and Analyze Data Draw Valid Conclusions NO Communicate Results Faulty Experiments? S C I E N T I F I C 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 I W M E T H O D

11 Scientific Method Let’s break each of these steps down into their individual components:

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

13 1. Observing Make an observation See something unusualAs we all know, frogs have four legs. Make an observation See something unusual Frogs with incorrect number of legs! What’s up with these froggies?

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

15 3. Researching Gather information related to the problemRead, 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 pollutants in the pond Change in amount of UV (sunlight) exposure on eggs Etc.

16 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

17 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!)

18 Hypothesizing 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 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 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? 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 Aliens from outer space- Sorry, this is not allowed because it is not testable using the Scientific Method.  Sheesh! 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 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 Loud Rock + Roll Music- Okay, this is testable, but WHY test it??? (get real)

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

20 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.

21 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 Spontaneous Generation (or actually that flies came from maggots, which came from flies) Francesco Redi (1668)

22 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

23 Belief based on prior observationsIf 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

24 Belief based on prior observationsRedi 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

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

26 Redi’s Controlled ExperimentRedi used two groups of jars Jars that contained meat and no cover Jars that contained meat and gauze cover Jars with meat Uncovered jars Covered jars

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

28 Variables in an ExperimentVariables - 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

29 Setting up a Controlled ExperimentIn 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

30 Variables in Redi’s ExperimentControlled Variables: jars, type of meat, location, temperature, time Manipulated Variables: gauze covering that keeps flies away from meat

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

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

33 6. Collect and Record Dataobservations and measurements made 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 that do not involve numbers, are of a descriptive nature i.e. white maggots covered the meat, leaves were all wilting

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

35 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!

36 9. Determine LimitationsScientists 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

37 10. Publish Results Communication is an essential part of scienceScientists 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

38 Repeating the InvestigationSometimes 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!

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

40 Scientific Method How Scientists Work Solving the ProblemsThe 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.

41 S C I E N T I F I C M E T H R E O V D I W

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

43 Steps of Scientific Method in order1 State the Hypothesis Make an Observation Define the Problem 2 the Problem 3 4 5 6 Analyze Data 7 8 9 10 Report Results Determine Limitations

44 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

45 Scientific Law Scientific Method Scientific laws represent the cornerstone of 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