Science and the Scientific Method

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Science and the Scientific Method
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Long Ago

• Until 1859 the common belief was that life could
  appear from non-living things.
• This was called spontaneous generation.
• The Slow Death of Spontaneous Generation occurred
  from 1668 to 1859.
• ?What is spontaneous generation?

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Redis Experiment on Spontaneous Generation (1668)
Section 1-2
OBSERVATIONS Flies land on meat that is left
uncovered. Later, maggots appear on the meat.
HYPOTHESIS Flies produce maggots.
PROCEDURE
Uncovered jars
Covered jars
Controlled Variables jars, type of
meat, location, temperature, time
Several days pass
Independent Variables gauze covering that keeps
flies away from meat
Dependent 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.
Go to Section
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John Needham (1745)

• Everyone knew that boiling killed microorganisms
  (common knowledge)
• John Needham proposed to test whether or not
  microorganisms appeared spontaneously after
  boiling.
• He tried to disprove Redis conclusion
• He boiled chicken broth,
• put it into a flask,
• sealed it,
• and waited
• sure enough, microorganisms grew. Needham claimed
  victory for spontaneous generation.
• ?Do you see a problem with this experiment?

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Spallanzani

• You missed a variable, for life to be generated
  you need contact with the air
• Is this true?

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Figure 1-10 Spallanzanis Experiment
Section 1-2
Gravy is boiled.
Flask is open.
Gravy is teeming with microorganisms.
Flask is sealed.
Gravy is free of microorganisms.
Gravy is boiled.
?What is the difference between Needhams
Experiment and Spallanzanis Experiment?
Go to Section
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Figure 1-11 Pasteurs Experiment
Section 1-2
Broth is boiled.
Broth is free of microorganisms for a year.
Curved neck is removed.
Broth is teeming with microorganisms.
?How is Pasteurs experiment different from
Spallanzanis?
?When did the microorganisms begin to grow in
Pasteurs experiment?
Go to Section
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Scientific Theory

• Science Theory- an explanation of a natural
  phenomenon that is supported by a large body of
  scientific evidence obtained by many different
  investigations and observations.
• A theory remains valid only if every new piece of
  information supports it.
• If available information does not support a
  theory, then the theory is disproved. 
• New discoveries in science occasionally change a
  theory.
• ?Can a theory change and, if it does, how?
• Scientific Law- facts of nature that are
  generally known to be true. Stronger than a
  theory

Hypothesis? Theory ? Law
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Nature of Science

• Science never reaches Fact
• Constantly, new technologies and ideas arise that
  disprove current theories.
• Science gets as close to Fact as possible as
  people fail to disprove a concept.
• ?Why does science never reach fact?

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Recipe for Bees About 2000 years ago, a Roman
poet wrote these directions for producing
bees. Is this science and is this an experiment?
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Yes!At the time with the current knowledge this
could be repeated and have a similar result
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What IsThe Goal of Science

• To investigate and understand nature
• To explain events in nature
• To use those explanations to make useful
  predictions

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Scientific Method1. Problem2. Research3.
Hypothesis4. Experiment5. Analysis6. Conclusion
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• Independent Variable is the amount of sugar.
• Dependent variable was density we wanted to see
  if water would float.
• Control the water
• Constant The amount of water, dye, spoons, cups,
  test tubes, temp,
• ProcedureMixed measured water, sugar with water,
  dye then we put it in a test tube.

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• Then put food coloring in the other water then,
  tilted test tube poured in the water inside the
  tube and tested it to see if it would float.
• Results Water can float on a sugar solution.

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Scientific Method

• Identify the Problem predict outcome?
• Form a Hypothesis
• Set Up a Controlled Experiment
• Record and Analyze Results
• Draw a Conclusion
• Repeat and Retest magic is 3 of same! 

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Vocabulary

• Hypothesis A prediction about a possible answer
  to a scientific question.
• What will happen to the independent variable and
  the dependent variable during the expermiment.
• The plant is dying because it needs to be
  watered.

It is a statement which is an educated guess and
it is testable
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Vocabulary

• Independent variable The variable you the
  scientist change in an experimental group.
• Cause
• Often graphed on the X-Axis

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Vocabulary

• Dependent variable Part of the experiment that
  a scientist wants to observe and measure.
• You do not have direct control over the results
  of this variable.
• Effect
• Graphed on the Y-Axis
• ExampleHow low did the blood sugar drop?

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Vocabulary

• Experimental group In an experiment this is the
  group that the independent variable IS given to.
  It is compared to the control group.

Control Group Plant B is left the same (not
watered)
Experimental Group Plant A (watered)
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Vocabulary

• Control group
• the group that is used compare your results
• this is the group you do NOT give your
  independent variable.
• Often is give the Placebo (FAKE PILL)
• Controls are needed to eliminate other
  explanations of experimental results. For
  example, suppose a researcher feeds an
  experimental artificial sweetener to thirty
  laboratory rats and observes that eight of them
  die of dehydration.
• Can we determine without doubt that the
  artificial sweetener killed them?
• The underlying cause of death could be the
  sweetener itself or something unrelated.

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Vocabulary

• Independent variable Part of the experiment
  that a scientist purposely changes also known as
  manipulated variable
• Dependent variable Part of the experiment that
  a scientist wants to observe, which may change in
  response to the manipulated variable also known
  as a responding variable. You do not have direct
  control over this variable.
• Controlled variable- All the variables that are
  kept the same (held constant during the entire
  experiment.

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DR. S Insulin Pill
Patient Start Blood Sugar Level Final Blood Sugar Level
Student 1 185 125
Student 2 184 184
Student 3 185 185
Student 4 186 124
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The Effect of Fertilizer on Plant Growth

• Question Will fertilizer increase plant growth?
• Hypothesis
• Materials Tomato seeds, Water, Flower pots
• Miracle Grow fertilizer
• Variables
• Independent Variable
• Dependent Variable
• Control
• Constants

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Results
Plant Day 11 Day 12 Day13 Day 14
Control 1 0 cm 0 cm .25 cm 1.0 cm
Control 2 O cm 0 cm .75 cm 1.1 cm
Fertilizer 1 .5 cm 1.4 cm 4.9 cm 5.9 cm
Fertilizer 2 1.0 cm 1.8 cm 4.5 cm 5.8 cm
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• Results

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Vocabulary

• Controlled experiment a test of the effect of a
  single variable keeping all other variables the
  same.
• Change only one variable in an controlled
  experiment
• Variable anything that you change or changes as
  a result of what you do

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Vocabulary

• Dependent variable Part of the experiment that
  a scientist wants to observe, which may change in
  response to the manipulated variable also known
  as a responding variable. You do not have direct
  control over this variable.

Die
Why is the dependent variable referred to as The
Effect? The dependent variable is dependant on
the independent variable
Live
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• I want to know if more light would cause hens to
  lay more eggs.
• In this experiment, what would be the only thing
  (variable) I would want to change?
• Why would I not want to also change the amount of
  food I give them?

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Explaining the evidence

• Hypothesis- a statement that is a possible
  explanation for a set of observations or answers
  to a scientific question
• A hypothesis must be testable. (not useful if it
  cant be tested)

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Vocabulary

• Experiment
• Data collection collection of evidence inform
• Data Analysis Make a graph from the information
  gathered from observations

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Vocabulary

• Observation - use of one or more of the
  sensessight, hearing, touch, smell, and
  sometimes tasteto gather information
• Qualitative observations involve characteristics
  that cannot be easily measured or counted. These
  are descriptions.
• Quantitative observations involve numbers

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Vocabulary

• Data analysis - Observing your data, picking out
  the important results, and making sense of the
  data.
• Graphs are very useful in analyzing data
• Data is anything collected through observation in
  an experiment

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A few types of graphs

• Line Graph
• Bar Graph
• Pie Chart

There are times where one graph is far better
than the others
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Vocabulary

• Inference - logical interpretation based on prior
  knowledge and experience
• For example, researchers might test small
  quantities, or samples, of water from a
  reservoir. If samples collected from different
  parts of the reservoir are all clean enough to
  drink, the researchers may infer that all the
  water in the reservoir is safe to drink.

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Vocabulary

• Conclusion - Using the evidence of an experiment
  to determine whether the hypothesis was supported
  or refuted (wrong).

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State the Problem
Scientific Method
It Stinks!
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Form a Hypothesis
Scientific Method

• The room stinks because a rat died in a cabinet
• The room stinks because someone passed gas
• Pick only one hypothesis to test, you can come
  back to the others if you conclude the first one
  is wrong.
• Pick the most likely hypothesis to test first

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Set Up a Controlled Experiment
Scientific Method

• Have a control to compare your results to- in
  this case the room before to odor
• Only Change One Variable
• The variable changed must make sense
• I will turn on the exhaust and see if it still
  smells bad 5 minutes later
• If it does not smell bad it was only something
  temporary

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Record and Analyze Results
Scientific Method

• It still smells bad after 5 minutes

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Draw a Conclusion
Scientific Method

• My Hypothesis about the flatulence was incorrect?
  go back to step one and test another hypothesis

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Station 3

• 1. Define abiogeneisis
• 2. What is the control variable of this
  experiment?
• What is the Independent variable of this
  experiment?
• Did li

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Station 2

• What did Louis Pasteur discover?