Honors Biology Laboratory Skills

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The Scientific Method

• Honors Biology Laboratory Skills

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The Scientific Method

• Making Observations
• Asking Questions
• Forming a Hypothesis
• Designing an Investigation
• Testing the Predictions (Collecting, analyzing,
  processing data)
• Conclusion

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Hypotheses and Predictions

• A scientific hypothesis is a possible explanation
  for an observation or a scientific problem that
  is given to you. Its characteristics
• It offers an explanation for an observation
• It refers to only one independent variable
• It is written as a statement
• It is testable by experimentation
• It is based on research, observations or prior
  knowledge
• It leads to predictions about the system (or the
  topic of your experiment)

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Hypotheseslets give it a try!

• Example 1 During an experiment on bacterial
  growth, the girls noticed that bacteria in
  cultures grew at different rates when the dishes
  were left overnight in different parts of the
  laboratory. (This is an observation)
• Hypothesis

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Hypothesesone more try!

• Example 2 Observation During an experiment on
  plant cloning, a scientist noticed that the root
  length of plant clones varied depending on the
  concentration of a hormone added to the agar.
• Hypothesis

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Variables

• You must identify the variables that you are
  testing and the ones that you keep constant.
• A variable is any characteristic or property that
  is measurable or observable.
• You must use units with your variables
• Types of variables
• Independent variable
• Dependent variable
• Controlled variable (constants)

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Independent Variable

• Set by the person carrying out the investigation
  (ex. Temperature, light intensity, pH)
• Recorded on the x axis of the graph during data
  presentation
• There is always only one in an investigation
• Must record proper unit

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Dependent Variable

• Measured during the investigation (ex. Plant
  growth, heart rate etc)
• Recorded on the y axis of the graph during data
  presentation
• There is always only one in an investigation
• Must record proper unit

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Controlled (Constant) Variables

• Factors that are kept the same or controlled.
• List these in the method as appropriate to your
  own investigation

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Lets play with variables! (dont need to write
this down)

• Look at the picture and explanation on the board
  on catalase activity and answer the following
  questions
• 1. Write a suitable hypothesis for this
  experiment
• 2. Name the independent variable with the proper
  unit ___________________________
• 3. List the equipment needed to set the
  independent variable, describe how it was used
• 4. Name the dependent variable with the proper
  unit ___________________________
• 5. List the equipment needed to measure the
  dependent variable, describe how it was used
• 6. List three variables that might have been
  controlled in this experiment

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Data Collection

• Design a data table to record your results. Your
  data table should clearly show the units and
  values of the independent and dependent
  variables.

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Data Presentation -- Types of Graphs

• Some examples that we use this year
• Line Graph
• Bar Graph
• Pie Graph
• Your graphs should always include the following
• Labeled axes with units
• Connected dots for line graphs
• Proper scale
• Title of the graph

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Line Graph

• Line graphs are used when one variable (called
  the independent variable), affects another, the
  dependent variable.
• The data for line graphs must be continuous for
  both variables.

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Bar Graph

• The data for this graph are non-numerical and
  discrete for at least one variable, in other
  words, they are grouped into separate categories.
  There are no independent or dependent variables.
• The data are discontinuous, so the bars do not
  touch
• Multiple data sets can be displayed using
  different colored bars placed side by side within
  the same category.

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Pie Graphs

• The entire chart always represents 100
• Must determine what the 100 (whole pie) stands
  for.
• Best to use when we compare parts of a whole.

Land Use in North Carolina
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What Is a Scientific Model?

• A scientific model is a representation of an
  object or system. An example of a scientific
  model would be a diagram of a cell or a map ..
  Even a model rocket!
• Any model is based on a certain set of
  observations. A good model must be able to
  explain as many characteristics of these
  observations as possible, but also be as simple
  as possible.

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• And as a review, watch http//www.youtube.com/wat
  ch?vjPaGOHwv7mQ