4. Designing an Experiment
1. Make Observations/Ask a Question
2. Research/Form a Hypothesis
4. Record and Analyze Results
5. Draw a conclusion
• Communicate Results
• Repeat
5. Set up a Controlled Experiment
• Use only one variable
• Control (keep unchanged) all others
• Manipulated variable is changed
• Responding variable is observed
• Francesco Redi (1668)
• Needham (1748)
• Lazzaro Spallanzini (1765)
• Louis Pasteur (1800's)
12. Practice the Scientific Method
• Think about how you would test
how the amount of a certain
fertilizer determines if the fertilizer
would grow taller plants.
13. Brainstorm
• Decide how you would go about conducting an
experiment or investigation to study this.
• Identify the Dependant Variable and the Independent
Variable
• I will provide you results
14. Data
Does more fertilizer = better growth?
Analyze these results.
15. What if you Cannot Experiment?
• When might an experiment not be possible?
• How can we answer scientific questions without
experimentation?
Models
Human studies (how a drug effects human – ethical)
Field studies can be used for wild creatures – observing nature in its natural state)
Try to identify and control as many variables as possible
Models – using computers to make representations of processes, ideas, or structures.
Observational studies – No manipulation
A theory develops when a hypothesis becomes well-supported (Ex: Theory of Biogenesis)
Theory - a well-tested explanation that unifies a broad range of observations. NOT ABSOLUTE
A scientific theory is a well-substantiated explanation of some aspect of the natural world that is acquired through the scientific method, and repeatedly confirmed through observation and experimentation.
Theories can be revised or replaced if new evidence is discovered
Evolution by natural selection
Cell theory is a scientific theory which describes the properties of cells
The Gene Theory is one of the basic principles of biology. The main concept of this theory is that traits are passed from parents to offspring through gene transmission.