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					Scientific Method
• Identify the steps used in scientific
• Explain why scientists use scientific
• Explain how scientific knowledge can
• Explain how scientific methods are used
  to answer questions and solve problems.
• Formulate testable hypotheses.
• Use information in tables and graphs to
  analyze experimental results.
What Are Scientific Methods?
 • Scientific methods are the ways in which
   scientists answer questions and solve
 • When scientists try to solve a mystery, they
   perform problem-solving procedures called
   scientific methods.
 • As scientists look for answers, they often use
   the same steps. But there is more than one
   way to use the steps. Scientists may repeat
   some steps or do them in a different order.
 • When you use methods like these, you are
   solving problems in a scientific way.
Steps of the Scientific Method
• Identify the Problem (ask a question)
• Research (make observations/gather
•   Form a Hypothesis
•   Test the Hypothesis
•   Analyze Data/Results
•   Draw a Conclusion
•   Communicate Results
    Remember scientists may repeat
    some steps or do them in a different
Identify the Problem (ask a question)
• Asking a question helps focus the
  purpose of an investigation. Scientists
  often ask a question after making
• An observation is any use of the senses to
  gather information.
• Observations should be accurately
  recorded so that scientists can use the
  information in future investigations.
What is in this box?
Research (make observations/gather information)
    • Early people relied on mythology to explain what
      they observed. They believed that mythological
      gods were responsible for creating storms, causing
      volcanoes to erupt, causing earthquakes, bringing
      the seasons, and making comets appear in the
    • Some early civilizations went so far as to record
      what they saw.
    • They developed calendars that described natural
      recurring phenomena.
    • Later, civilizations created instruments to measure
    • As instruments became better, accuracy of
      observations improved.
    • While observations were being made, people
      made inferences, or conclusions, to help explain
Research (make observations/gather information)
    • Any information that you gather through
      your senses is an observation. Take a
      look around to find answers to your
    • Look up information in reliable resources
      such as textbooks, encyclopedias, and
      magazines or a quality search on the
    • Remember observations lead to answers
      only when they are accurate and carefully
       Form a Hypothesis
• Once you have asked a question and made
  observations, you are ready to form a hypothesis.
• A hypothesis is a possible explanation or answer
  to a question that is based on prior scientific
  research or observations that can be tested
  (educated guess).
• A statement of cause and effect that can be used
  to set up a test for a hypothesis is called a
• Make Predictions Before testing a hypothesis,
  scientists often make predictions about what they
  think will happen in an experiment or
      Researching on the Web
• Use specific keywords, try a variety
• Use quotation marks; but not too much
• Usually the first 15-20 sites on a list are
  the most useful otherwise you need to
  revamp your search
• Sites ending in .edu, .org, and .gov are
  usually more reliable than .com and .net
• Organizations websites (NASA, USGS, etc)
  often contain sites for students
         Evaluating Sources
• Determine when it was written (use the
  most recent verifiable data)
• Determine who wrote it
• Determine the authors purpose for writing
• Determine who the original audience was
• If in doubt verify with other sources
  A stapler
     Test the Hypothesis
• After you form a hypothesis, you must
  test it. Testing helps you find out if your
  hypothesis is correct or not.

• A hypothesis must be tested for
  scientists to learn whether an idea can
  be supported scientifically. Scientists
  test hypothesis by gathering data.
      Test the Hypothesis
• Data are any pieces of information acquired
  through observation or experimentation.
• Designing an Experiment Designing a good
  experiment requires planning and a consideration
  of all factors.
• Keep It Under Control A controlled experiment
  may be used to test a hypothesis. A controlled
  experiment tests only one factor (variable) at a
  time and consists of a control group and one or
  more experimental groups. By changing only the
  variable, scientists can see the results of just that
  one change.
• Collecting Data Scientists keep clear, accurate,
  honest records of their data so that other scientists
  can repeat the experiment and verify the results.
   Test the Hypothesis
Make a box with a stapler in it and
    compare it to the original
• After you have decided how you
  will conduct an experiment, you
  can begin testing.
• During the experiment, you
  should observe what happens
  and carefully record your data in
  a table.
• When you are making and
  recording observations, be sure
  to include any unexpected
• Many discoveries have been
  made when experiments
  produced unexpected results.
     Experiment Ground Rules
• Plan the experiment in ADVANCE
• For your results to be valid or reliable,
  your tests should be repeated many times
  to see whether you can confirm your
  original results.
    • If something in an experiment only occurs once,
      you cannot base a scientific conclusion cannot be
• Also, the number of samples being tested
  should be large.
• Report ALL results even unexpected ones
Variables vs. Controls in Experiments
• Variables
       • Changeable factors in an experiment
       • Independent variable- the ONE factor changed by the
         experimenter for testing purposes
       • Dependent variable- the factor being measured in the
         experiment. It changes BECAUSE of the independent variable.
• Constants
      • Factors in an experiment that DO NOT change.
      • Basically Everything Else
• Control
      • Compare results

Example Experiment:
          Does popcorn pop better when cold?
Independent Variable = Temperature of popcorn
Dependent Variable = Number of popped kernels
Controls = Brand and type of popcorn, cook time and style, etc.
      Analyze Data/Results
• After they finish their tests, scientists must
  analyze the results. Analyzing the results
  helps scientists explain and focus on the
  effect of the variable.
• Analyzing the results helps scientists
  construct reasonable explanations based
  on the evidence that has been collected.
• Once you have your data, you must
  analyze them to find out whether the
  results support your hypothesis.
            Analyze Results
Can it be a stapler?
       Draw a Conclusion
• At the end of an investigation, you must
  draw a conclusion. Your conclusion can
  help you decide what you do next.
• Scientists must conclude if the results
  of their tests support the hypothesis.
  Proving that a hypothesis is not true
  can be as valuable as proving that it is
              What Next?
•   New Hypothesis
•   Repeat Experiment
•   Analyze Data
•   Communicate Results
     Communicate Results
• Science depends on sharing information.
• One of the most important steps in an
  investigation is to communicate your results
  accurately and honestly.
• After finishing an investigation, scientists
  communicate their results to share what they
  have learned.
• Sharing allows other scientists to repeat
  experiments to see if they get the same
• By sharing, scientists can compare
  hypotheses. Sometimes, new data lead
  scientists to change their hypotheses.
        Changes in Science
Today, everything known in science
results from knowledge that has been
collected over time. Science has changed
and will continue to change because of
continuing research and improvements in
instruments and testing procedures.
Changes in Science
Summing up the Scientific Method
• Determine the problem
      • What do you want to know?
• Research
      • Look for information on the topic
• Make a hypothesis
      • A hypothesis is an educated guess.
      • I think this will happen BECAUSE…
• Test Your Hypothesis
      • Design an experiment to check your ideas.
• Analyze the results
      • Study the data to determine the results
• Draw Conclusions
      • Create a theory based on the data.
• Communicate the Results
      • Provide results for critical reviews from peers
       Science All Around
• Scientific methods include
  identifying a problem or question,
  gathering information, developing
  hypotheses, designing an
  experiment to test the hypotheses,
  performing the experiments,
  collecting and analyzing the data,
  and forming conclusions.
• Science experiments should be
  repeated to see whether results are
       Science All Around
• In an experiment, the independent
  variable is the variable being
  tested. Constants are variables
  that do not change. The variable
  being measured is the dependent
  variable. A control is a standard
  to which things can be compared.
• Technology is the use of scientific
Diagram of the Scientific Method
Diagram of the Scientific Method
Diagram of the Scientific Method

               Remember scientists
               may repeat some
               steps or do them in a
               different order.
Scientific Method
     A Real-World Question
• Engineers are scientists who put scientific knowledge
  to practical human use.
• Engineers create technology. Technology is the
  application of science for practical purposes.
• Engineers Czarnowski and Triantafyllou studied the
  efficiency of boat propulsion systems.
• Efficiency compares the energy used to move an
  object (the boat) forward with the energy supplied by
  the machine (engine).
• The Importance of Boat Efficiency. Making boats more
  efficient would save fuel and money.
• Based on their observations, Czarnowski and
  Triantafyllou asked the question: How can boat
  propulsion systems be made more efficient?
Nature Provides a Possible Answer
  Czarnowski studied penguins
  swimming and formed the
  hypothesis: A propulsion system
  that mimics the way a penguin
  swims will be more efficient than a
  propulsion system that uses
       Testing Proteus
• Czarnowski and Triantafyllou built a
  model penguin boat called Proteus
  to test their hypothesis.
• The engineers took Proteus into
  open water to collect data.
• Pieces of information acquired
  through observation or
  experimentation is called data.
              Data from Proteus

The graphs above show the analysis of the tests done on Proteus.
  The Proteus Conclusion
Czarnowski and Triantafyllou found
that the penguin propulsion system
was more efficient than a propeller
system. So, they concluded that
their hypothesis was supported.
Communicating About Proteus

Czarnowski and Triantafyllou published
their results in academic papers. They
also displayed their project and its
results on the Internet.
      Online Scenario

The scientific method in action

           code CGP-6012
    Think Teenage Science
• List the steps of the scientific method
  on the left side of your paper

• Create a teenage problem that you
  could use the scientific method to solve
  and state how each step would be used
       Question 1
Explain how developing a hypothesis is
different from just taking a guess.
A hypothesis is based on observations and is
grounded in what is already known.
      Question 2
Which is an appropriate question for science to

A. Does breaking a mirror cause bad luck?
B. What birds prefer nesting in low shrubs?
C. What brand of fertilizer should farmers use?
D. Which type of rose produces the most
   pleasing scent?
The answer is B. Questions that involve
judgments about beauty or matters of opinion
are not in the realm of science.
       Question 3
Which of the following is a scientific question?

A. How long should you cook a steak?
B. What’s your favorite color?
C. What career should you choose?
D. What makes your eyes the color they are?
The answer is D. The study of genetics can tell
you why your eyes are the color they are.
      Question 4
Explain the difference between a constant and
a control.
A constant is a factor that does not change
when other variables change. A control is the
standard by which test results are compared. A
control is necessary in every experiment for the
results to be valid.
       Question 5
You conduct an experiment to test the effect of
sunlight on plant growth, and give the same
amount of water to all plants. Is the amount of
water given to the plants a constant or a control?
             Trial #1       Trial #2     Trial #3

 Plant A    30 minutes     30 minutes   30 minutes

 Plant B    60 minutes     60 minutes   60 minutes

 Plant C     4 hours        4 hours      4 hours
Since all trials use the same amount of water, it
is a constant.
      Question 6
In an experiment designed to test the effect of
fertilizer on plant growth, which of these is a

A. plants receiving 10 mg per plant biweekly
B. plants receiving 20 mg per plant biweekly
C. plants receiving 30 mg per plant biweekly
D. plants receiving no fertilizer
The answer is D. A control is a standard used
for reference. The plant group receiving no
fertilizer is a control because growth in this
group occurs in the absence of the variable
being tested. Plant growth in the experimental
groups can be compared to that in the control
group to determine the effect of the fertilizer.
      Question 7
Which word refers to variables in experiments
that do not change?

A. constants
B. controls
C. data
D. hypothesis
The answer is A. Constants are variables that
are not changed. Controls are standards for
  Question 8

1. If the groups were not labeled, how could you tell
   which group was the control group?
2. Why is it important to have a control group when
   doing an experiment?

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