The Scientific Method in Action

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The Scientific Method in Action
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SCIENCE

• If you dont make mistakes, youre doing it wrong
• If you dont correct those mistakes, youre doing
  it really wrong
• If you cant admit that youre mistaken then
  youre not doing it at all!

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What is Science?

• (verb) it is an activity carried out by
  scientists, with certain raw materials, purpose
  and methodology in order to gain knowledge
• (noun) it is the result of this activity a
  well-established and well-tested body of facts,
  laws and models that describe the natural world.

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• Science involves the critical evaluation of ideas
  and information
• Scientists maintain a healthy skepticism about
  information and ideas
• the best way to evaluate ideas is the scientific
  method
• Only field where ideas are tested

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Where do we get knowledge?

• Acceptance of truth
• From inherited customs, traditions
• Authority figure
• Trial and error
• Deductive reasoning
• Assumptions from existing knowledge
• Uses logical arguments (If then)

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In God We Trust all others must have data
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Scientific Method

• Scientific knowledge begins with an observation
  and a proposed explanation.
• Explanation called a hypothesis
• A hypothesis is testable and falsifiable
• In science hypotheses are tested by using them to
  make predictions about the outcome of an
  experiment

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(a) Describe how scientific method involves
interplay between observations and the formation,
testing and evaluation of hypotheses.
The principle of scientific method is based on
the collection of data by observation and
experimentation and the formulation of hypotheses.

• The hypotheses may be subsequently refined on the
  basis of the observations. Scientific research
  involves proposing hypotheses to explain observed
  phenomena, then designing and carrying out
  experiments to test the hypotheses.

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Scientific Method

• Scientific method
• More reliable for obtaining information
• You can test what you believe to be true
• Others can repeat your experiment
• Opportunity to prove false
• Follows general set of systematic procedures
• Steps are followed in order to answer a research
  question

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Ethics
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The Scientific Method

• Observe an event.
• Develop a Hypothesis which makes a prediction.
• Test the prediction.
• Observe the result.
• Revise the hypothesis.
• Repeat as needed.
• A successful hypothesis becomes a Scientific
  Theory.

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Scientific Method Everyday Science
Observation Spaghetti sauce is red.
Hypothesis (prediction) Use tomatoes.
Test Heat pot of tomato sauce.
Observe result Taste the sauce - bland.
Revise hypothesis? Use tomato sauce and garlic!
New test? Add garlic, taste - not so bland.
Scientific Theory Grandmas Recipe.
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Scientific Method Medical Science
Observation Patient has high cholesterol
Hypothesis (prediction) Certain chemicals may dissolve cholesterol deposits.
Test Give 100 patients these chemicals, give 100 patients placebo.
Observe result Same number lower their cholesterol as placebo patients.
Revise hypothesis? Try different combo of chemicals.
New test? Re-run medical test. Observe results.
Scientific Theory Lipitor reduces cholesterol.
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How many variables do you test at one time?
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Problem/Question

• John watches his grandmother bake bread. He ask
  his grandmother what makes the bread rise.
• She explains that yeast releases a gas as it
  feeds on sugar.

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Caution!

• Be careful how you use effect and affect.
• Effect is usually a noun and affect, a verb.
• The effect of sugar amounts on the rising of
  bread.
• How does sugar affect the rising of bread?

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Observation/Research

• John researches the areas of baking and
  fermentation and tries to come up with a way to
  test his question.
• He keeps all of his information on this topic in
  a journal.

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Formulate a Hypothesis

• After conducting further research, he comes up
  with a hypothesis.
• If more sugar is added, then the bread will rise
  higher.

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(b) Design experiments to test a given
hypothesis, in which variables are controlled and
quantitative results are collected.

• Candidates should be able to apply their
  knowledge of practical techniques to design
  experiments. As an example, to design an
  experiment to test the hypothesis that the rate
  of photosynthesis of an aquatic plant increases
  as light intensity increases. In this example, it
  is important to recognize that light intensity is
  the key variable and others, including
  temperature and the wavelength of light are the
  control variables. The effect of control
  variables should be eliminated by careful
  experimental design if valid results are to be
  obtained.
• The nature of the results obtained depends on the
  actual investigation, but could include
  measurements of volume, time, length, mass or
  temperature, with appropriate SI units. If a rate
  is measured, this should be expressed in relation
  to time.

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Ockams Razor

• It states that among competing hypotheses, the
  one with the fewest assumptions should be
  selected. Other, more complicated solutions may
  ultimately prove correct, butin the absence of
  certaintythe fewer assumptions that are made,
  the better.

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(d) Formulate a hypothesis on the basis of
experimental data.

• With reference to experimental data, candidates
  should be able to state an operational
  hypothesis. For example, a table of data might
  suggest that, as the concentration of nitrate
  ions increases, the growth of algae also
  increases. From the data, candidates could
  suggest the hypothesis that there is a positive
  relationship between the concentration of nitrate
  ions and the growth of algae.

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Hypothesis

• The hypothesis is an educated guess about the
  relationship between the independent and
  dependent variables.
• Note These variables will be defined in the next
  few slides.

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Problem/Question

• John wonders if the amount of sugar used in the
  recipe will affect the size of the bread loaf?

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Independent Variable

• The independent, or manipulated variable, is a
  factor thats intentionally varied by the
  experimenter.
• John is going to use 25g., 50g., 100g., 250g.,
  500g. of sugar in his experiment.

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Dependent Variable

• The dependent, or responding variable, is the
  factor that may change as a result of changes
  made in the independent variable.
• In this case, it would be the size of the loaf of
  bread.

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Control Group

• In a scientific experiment, the control is the
  group that serves as the standard of comparison.
• The control group may be a no treatment" or an
  experimenter selected group.

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Control Group

• The control group is exposed to the same
  conditions as the experimental group, except for
  the variable being tested.
• All experiments should have a control group.

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Control Group

• Because his grandmother always used 50g. of
  sugar in her recipe, John is going to use that
  amount in his control group.

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• Independent variable condition or event under
  study (only 1 can reliably be tested at one time)
  
• Dependent variable condition that could change
  under the influence of the independent variable
  (what you measure)
• Controlled variables conditions which could
  effect the outcome of the experiment so they must
  be held constant between groups
• This is especially important as your results have
  little significance without a controlled
  experiment. Remember, correlation does not
  equal causation
• Used for comparison

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Causation vs Correlation
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Constants

• Johns teacher reminds him to keep all other
  factors the same so that any observed changes in
  the bread can be attributed to the variation in
  the amount of sugar.

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Constants

• The constants in an experiment are all the
  factors that the experimenter attempts to keep
  the same.

• Can you think of some constants for this
  experiment?

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Constants

• They might include
• Other ingredients to the bread recipe, oven used,
  rise time, brand of ingredients, cooking time,
  type of pan used, air temperature and humidity
  where the bread was rising, oven temperature,
  age of the yeast

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Trials

• Trials refer to replicate groups that are exposed
  to the same conditions in an experiment.
• John is going to test each sugar variable 3 times.

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(e) Explain how inherent variations and
limitations in the measurement of experimental
data lead to uncertainty in the results

• Candidates should recognize the relationship
  between variability of experimental data and the
  validity of any conclusions drawn. Candidates
  should also be able to comment on how variability
  and accuracy may influence the validity of
  conclusions drawn from experimental data.

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Theories and Natural Laws

• Theory a description of the world that covers a
  relatively large number of phenomena and has met
  many observational and experimental tests
• Law of Nature theory (or group of theories)
  that has been tested extensively and seems to
  apply everywhere in the universe
• One test is worth a thousand expert opinions.
• Bill Nye

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Collect and Analyze Results

• John comes up with a table he can use to record
  his data.
• John gets all his materials together and carries
  out his experiment.

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Size of Baked Bread (LxWxH) cm3
Size of Bread Loaf (cm3) Trials
Amt. of Sugar (g.) 1 2 3 Average Size (cm3)
25 768 744 761 758
50 1296 1188 1296 1260
100 1188 1080 1080 1116
250 672 576 588 612
500 432 504 360 432
Control group
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Collect and Analyze Results

• John examines his data and notices that his
  control worked the best in this experiment, but
  not significantly better than 100g. of sugar.
• John rejects his hypothesis, but decides to
  re-test using sugar amounts between 50g. and
  100g.

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Can you tell which group did the best?
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Size of Baked Bread (LxWxH) cm3
Size of Bread Loaf (cm3) Trials
Amt. of Sugar (g.) 1 2 3 Average Size (cm3)
50 1296 1440 1296 1344
60 1404 1296 1440 1380
70 1638 1638 1560 1612
80 1404 1296 1296 1332
90 1080 1200 972 1084
Control group
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Conclusion

• John finds that 70g. of sugar produces the
  largest loaf.
• His hypothesis is accepted

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(f) Demonstrate an understanding that a
hypothesis that is consistently supported by
experimental testing can become a theory.

• A hypothesis is a proposed explanation for an
  observed phenomenon, which can then be rigorously
  tested using scientific method. A hypothesis may
  be regarded as a prediction if this is supported
  by experiments that confirm the hypothesis, the
  hypothesis may be put forward as a theory.

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g) Explain the meaning of the term theory with
reference to examples from the Subject Content

• A scientific theory is supported by a number of
  testable statements and is used as a general
  principle to explain a phenomenon. Scientific
  theories are intended to be accurate, predictive
  models of the natural world. Examples in the
  syllabus include the Darwin-Dana-Daly theory of
  atoll formation and the theory of plate tectonics

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Graphs

• Graphs help us visualize numerical data.
• There are several different types of graphs
• Bar graphs
• Pie graphs
• Line graphs

Candidates should be able to recognize trends in
data presented in the forms of tables or in
graphical form. For example, they should be able
to recognize whether or not there is a
relationship between two variables and to comment
on this in the context of a stated hypothesis.
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• IF.THEN
• If independent variable
• What is being manipulated (basis of your
  hypothesis)
• Control group your experiment WITHOUT this
  group
• X axis
• Then dependent variable
• What youre measuring
• Y Axis

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Qualitative vs Quantitative

• Just as its necessary to observe, its also
  important to quantify observations in some way
• For example define tall

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Bar Graphs

• Bar graphs are used to show a comparison of
  multiple objects.

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Pie Graphs

• Pie graphs are used to compare the parts of a
  whole.

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Line graphs

• Line graphs are used to show the relationship
  between variables.

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Right from Wrong

• The theory of gravity, theory of electricity,
  the germ theory of disease, and the theory of
  evolution are tested, accepted explanations for
  events that occur in nature.
• Theories can really never be completely proven,
  only disproven. When new evidence comes along,
  we must modify our theory or at times even get
  rid of it and start over again

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The Need for Statistics

• How do you tell a really odd but correct result
  from a WRONG result?
• The simple answer is you can never tell for
  certain that a given result is wrong. All we
  can do is determine whether a given result is
  likely or unlikely.
• There are 2 ways of getting a weird statistical
  measurement an unusual result from the correct
  theory, or a result from the wrong theory. These
  are indistinguishable because of this fact,
  statistics is never able to discriminate between
  true and false with 100 certainty.

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Reasonability

• What is a reasonable result is subjective and
  arbitrary.
• For most work (and for the purposes of this
  class), a result is said to not differ
  significantly from expectations if it could
  happen at least 1 time in 20. That is, if the
  difference between the observed results and the
  expected results is small enough that it would be
  seen at least 1 time in 20 over thousands of
  experiments, we fail to reject the null
  hypothesis.
• For technical reasons, we use fail to reject
  instead of accept.
• 1 time in 20 can be written as a probability
  value p 0.05, because 1/20 0.05.
• Another way of putting this. If your
  experimental results are worse than 95 of all
  similar results, what you measured was very
  unlikely.

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Critically Thinking

• Identify and evaluate premises and conclusions in
  an argument
• Analyze conclusions based on evidence versus
  those based on value judgments
• Assign weight to opposing viewpoints based on
  chains of reasoning, sources of information
  (reliability)
• Adjust weighting depending on relevance to
  central issue, lack of specific evidence or
  contradictions

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