Scientific Method
Not everything that counts can be counted, and not everything that can be counted counts‐Sign Hanging out of Albert Einstein's Office
• An organized plan for gathering, organizing, and communicating information is called a scientific method
• The goal of any scientific method is to solve a problem or to better understand an observed event.
• Copy the chart on page 8 in your textbook
Steps to Scientific Method
• Scientific investigations begins with observations. • An observation is information that you obtain through your senses. • Repeatable observations are known as facts. • Can you list some facts?
• After observing nature, the next step is asking or forming a question about an observation.
• Examples: Why is water wet? Why are plants wet in the morning?
• Think of one and write it down.
Form a Hypothesis
• A hypothesis is a proposed answer to a question. • For a hypothesis to be useful, it must be testable.
• Examples: Water will freeze at 0 degrees Celsius Testing a Hypothesis
• Scientists perform experiments to test their hypotheses. • In an experiment, any factor that can change is called a variable.
• A manipulated variable causes a change in another variable.
• A responding variable is the variable that changes in response to the manipulated variable.
• A controlled experiment is an experiment in which only one variable, the manipulated variable, is deliberately changed at a time. • While the responding variable is observed for changes, all other variables are kept constant, or controlled.
Drawing Conclusions
• After you check your hypothesis you draw a conclusion based on data from the experiment
• What happens if the data do not support the hypothesis? • In such a case, a scientist can revise the hypothesis or propose a new one, based on the data from the experiment. • A new experiment must then be designed to test the revised or new hypothesis.
Developing a Theory
• A scientific theory is a well‐tested explanation for a set of observations or experimental results.
• Theories are never proved. Instead, they become stronger if the facts continue to support them.
• If an existing theory fails to explain new facts and discoveries, the theory may be revised or a new theory may replace it.
Scientific Law
• After repeated observations or experiments, scientists may arrive at a scientific law. • A scientific law is a statement that summarizes a pattern found in nature.
• A scientific law describes an observed pattern in nature without attempting to explain it. • The explanation of such a pattern is provided by a scientific theory.
Scientific Models
• In science we use models, or representation, of an object or event.
• Scientific models make it easier to understand things that might be too difficult to observe directly.
• Example: A globe is a model of the earth.
• Models don’t need to be physical objects, they can be ideas as well. Read the following experiment
and answer the questions.
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Mary had observed that bean plants seemingly grew taller when Fertilizer A was applied. She decided to conduct an experiment with bean plants to determine which type of fertilizer would produce the tallest bean plants in a 90 day period. She selected three containers of the same exact size and placed the same amount of potting soil in each container. She placed 100 bean seeds in each of the three containers. Each seed was planted the same distance apart in each container. She placed all three containers on the covered back porch. She added FERTILIZER A to one container and FERTILIZER B to another container. SHE DID NOT FERTILIZE THE PLANTS in the third container. She watered the three containers of plants every other day for 90 days. She watered with the same amount of water and distributed the water evenly in each of the three containers. At the end of 90 days, the container of plants receiving FERTILIZER A produced plants with an average plant height of 17 inches. FERTILIZER B plants averaged 12 inches, and the container receiving no fertilizer averaged 10 inches in height.
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Name the variables_________________________________
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Name the manipulated variable.______________________
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Name the responding variable.____________________________________
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What is the hypothesis _____________________________________
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State the number of repeated trials or repetitions._________________
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State the outcome of the experiment._____________________________
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Was the hypothesis correct?______________________
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Was this experiment controlled?____________Explain the rationale for your response.