methods of science chapter 1.3 pages 16-21. at the end of this chapter you should be able to…....
TRANSCRIPT
Methods of ScienceChapter 1.3 pages 16-21
At the end of this chapter you should be able to….
• Describe the difference between an observation and an inference.
• Differentiate among control, independent variable and dependent variable.
• Identify the scientific methods a biologist uses for research.
Scientific Method
• The scientific method generally follows the following pattern:
– Ask a question– Make observations– Form a Hypothesis– Experiment– Collect and analyze data– Draw conclusions
Ask A Question• Scientific inquiry begins with observation,
observation is the act of noting or perceiving objects or events using the senses
• Combining your observation with your past knowledge allows you to make inferences, or logical conclusions.
Observation vs. Inferences
• Inferences are an explanation for a observation that you have made.
• Inferences often change when new observations are made.
Observation: The grass is wetInferences: it rained
the sprinklers went off
Hypothesis
• a hypothesis is a TESTABLE explanation for your question.
– this statement can be tested by additional observations or experimentation
– an educated guess based on what is already know
Experiment
• experiment – a planned procedure to test a hypothesis
• controlled experiment – an experiment where an experimental group is compared to a control group– control group is a group in an experiment that
receives no experimental treatment– An experimental group is the group exposed to
the factor being tested
Experimental Design
• both control and experimental groups are designed to be identical except for one variable
• the factor that is varied in an experiment is called the independent variable
• the variable that is measured in an experiment is called the dependent variable
• a constant is a factor that remains fixed during an experiment
Collect and Analyze Data
• Data is any information gained from observations.
• 2 types: • Quantitative – measureable or countable
» 3 meters long» 4 marbles» 50 kilograms» 35 degrees Celsius
• Qualitative – describable, not measureable » red flowers» smells like fresh baked cookies» Tastes bitter
Collect and Analyze Data
• A graph of the data makes the pattern easier to grasp.
• On a graph, the x axis represents the independent variable
• the y axis represents the dependent variable
Conclusion
• once data are collected and analyzed, a hypothesis is either supported or rejected
• even when a hypothesis has not been supported, it is valuable.
• a hypothesis can be supported, but never proven because another experiment with new data can alter the conclusion
• Publication– scientists often publish the results of their
experiments for review and use by other scientists