Brain Teasers

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Brain Teasers
1. Which soldier is the largest?
C
B
A
2. How many legs does this elephant have?
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INVESTIGATION AND EXPERIMENTATION (I e)
What is Science?

• Observations, Inferences, and Controlled
  Experiments

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• 1. Science is an attempt to explain natural
  phenomenon.
• 2. All scientific knowledge is based on accurate
  observations of the natural world.

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• -An Observation an act of carefully watching
  something and collecting facts.
• -Observations are
• Gathered by using our senses (qualitative)
• Can also be gathered by taking measurements
  (quantitative)
• -Characteristics of good Scientific
  Observations
• Accurate Quantify or measure whenever possible
• Detailed and Complete Consider all parts of the
  observation
• Repeatable All observers see the same thing or
  each time the event is observed the description
  is the same

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• 4. There are two types of observations
• a) Qualitative ObservationsAn observation that
  describes the physical characteristics or
  qualities of something.
• (Ex. The water is hot The MM is small The
  egg smells bad The leaf is orange, etc)
• b) Quantitative ObservationsAn observation that
  is based upon numerical information or a
  measurement of some type.
• (Ex. The water is 45ºC The MM is 1.7 cm in
  length The car is traveling at 65 Km/hr)

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• 5. Good scientific observations are used in order
  to make predictions, or inferences, about the
  natural world.

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• 6. To infer means to make a prediction based on
  observation.
• 7. An inference is a conclusion that is formed by
  using logic and what is previously understood
  about the natural world.
• Ex Which statement is an inference?
• a. It has 3 candles.
• b. It is a cake for some one turning 3 years old.
• c. It is a round cake with squiggly black lines.

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• 8. Good scientific inferences
• a) Consider all available observations.
• b) Fits the understanding of the natural world
• c) are the most logical and rational conclusion.

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• 9. All inferences must be based on previous
  observations of the natural world.
• 10. Inferences are the basis for all Scientific
  Theories and Hypotheses.

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11. Whats the difference?

• Theory v. Law v. Hypothesis
• A scientific theory is a well-tested
  explanation that unifies a broad range of
  observations.
• (Ex Theory of Plate Tectonics, Evolution, Cell
  Theory, Germ Theory, etc.)
• -A scientific theory may be revised as new
  evidence is presented.
• -A theory is like the automobile.
• -WHY?? Components of it can be changed or
  improved upon, without changing the overall truth
  of the theory as a whole.

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• A scientific law is a consistent principle that
  is repeatedly observed in nature and is usually
  mathematical.
• -It is always true.
• (Ex Gravity, Speed of light, Newton's
  laws of motion, the laws of thermodynamics,
  Boyle's law of gases, the law of conservation of
  mass and energy, and Hooks law of elasticity. )
• A scientific law is like a slingshot.
• WHY?? A slingshot has but one moving part--the
  rubber band. If you put a rock in it and draw it
  back, the rock will fly out at a predictable
  speed, depending upon the distance the band is
  drawn back.

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12. Scientific Method and Controlled Experiments

• A hypothesis is a testable possible explanation
  of an observation.
• -In science, a hypothesis is useful only if it
  can be tested.
• -Scientific hypotheses are most often tested by
  the process of experimenting.
• An attempted explanation needs to be tested to be
  accepted.

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Scientific Method

• I. State the Problem
• II. Form a Hypothesis
• III. Set up a Controlled Experiment
• IV. Record and Organize Data
• V Formulate a Conclusion

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Scientific Method

• I. State the Problem Form of a question that
  indicates the purpose of the investigation.
• II. Form a Hypothesis This is a possible
  explanation or answer to the problem/question
  presented.
• (Hypotheses are not proven but supported by
  evidence)

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III. Set up a Controlled Experiment

• An experiment is basically a comparison of two
  situations.
• One of the situations is left constant, while
  one factor of the other situation is changed in
  order to test the affect of that specific change.
  
• Control a set of conditions used for comparison
  purposes can either be original conditions,
  real-life conditions, or specific conditions set
  by the experimenter

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• There are three types of factors that may affect
  an experiment. These factors are called
  variables.
• 1. The factor that is purposely changed by the
  experimenter is called the independent variable
• (also called the manipulated
  variable).
• 2. The factor that changes in response to the
  independent variable is called the dependent
  variable
• (or the responding variable).
• 3. The rest of the factors that the scientists
  keep the same in the experiment are called the
  controlled
• variables.

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• It is important to test the affect of changing
  only one variable in order to get accurate
  results.
• If only one variable is changed and all the
  other factors are kept the same then we say that
  it is a controlled experiment.
• Uncontrolled conditions can lead to inaccurate
  results.

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• IV. Record and Organize Data
• - Data tables, graphs, charts, observations,
  etc.
• V. Conclusion
• - Indicate whether or not your hypothesis was
  correct
• - Describe how the data provides evidence for
  your conclusion
• - Identify possible sources of error in your
  experiment

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Practice Problem

• 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 t his usual product. One
  test subject is sprinkled with the original
  itching powder, and another test subject was
  sprinkled with the experimental powder.
• Subject A 30 min itches
• Subject B 45 min itches

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Identify the

• 35. Control group - why?
• 36. Independent variable - why?
• 37. Dependent variable - why?

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Two Students were testing the amount of
fertilizer that would best promote the growth of
strawberries in a garden. Which could be
unavoidable sources of error?

1. Length of study
2. Variation in the strawberry plants
3. The cost of watering the plants
4. Fertilization during the study

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In most stable freshwater environments,
populations of Daphnia are almost entirely female
and reproduce asexually. However, males are
observed in low oxygen environments or when food
is scarce. Based on these observations, a
researcher suggests that male Daphnia develop in
response to unfavorable environmental conditions.
This is an example of a

1. Result
2. Theory
3. Procedure
4. hypothesis