The Scientific Method

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The Scientific Method

• Universal approach to problem-solving in science!!

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1. Ask a Question??(State the Problem) based
on observations

• Will the caffeine in coffee prevent mold growth?
• Does temperature affect the rate of diffusion?
• What wavelength of light do plants
  photosynthesize the best under?
• What brand of diapers is the most absorbent?

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2. Gather Background Information

• Go to library to find out what other similar
  questions scientists have asked and what
  conclusions they have come to.

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3. Hypothesis

• A testable explanation for a question or problem.
• an educated guess
• If plants reflect green light, then the rate of
  photosynthesis will decrease under green
  wavelengths of light."

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4. Experimentation

• Procedure that tests the hypothesis
• Controlled Experiment has 2 groups
• Control group all conditions are kept the same
  for comparison purposes
• Experimental group test group(s), only a
  single factor is changed INDEPENDENT VARIABLE.
  
• The change that results is called the DEPENDENT
  VARIABLE.

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Lets Practice.

• A team of students hypothesized that seeds
  would germinate faster at warmer temperatures.
  They divided 50 radish seeds into 2 identical
  pots and held all conditions light, water,
  fertilizer- the same except for temperature. One
  pot was kept at 18oC and the other at 25oC. They
  measured the number of seeds that germinated over
  10 days.
• Independent Variable ??
• Did you say temperature?
• Dependent Variable??
• Did you say of seeds germinated?

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Some more?

• A scientist hypothesized that tobacco plants
  would grow better with fertilizer. He took
  identical seeds, put in identical pots, watered
  the same amount, gave them the same amount of
  light, etc. The only thing different between the
  two plants was that one had fertilizer added to
  the soil and the other did not. He could then
  measure their growth.
• Independent Variable ?
• fertilizer
• Dependent Variable ?
• Rate of growth
• Control Group ?
• One without fertilizer
• Experimental Group ?
• One with fertilizer

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5. Collect Data

• Use your 5 senses to make OBSERVATIONS
• a. Quantitative ( 5 cm.)
• b. Qualitative subjective (tan in color)
• Usually recorded in tables, graphs, charts, etc.

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6. Analyze data draw conclusion!

• Report publish results when a scientists
  data supports the hypothesis it is supported by
  additional experiments.becomes a THEORY.
• For example, the cell theory.
• If hypothesis is not supportedreject or revise,
  ask new questions and test again.