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Scientific Method

Lesson: 05
Unit: 0
State Content Standard: Investigation & Experimentation

Lesson Title: Scientific Method
Textbook page: Not in textbook
Chemistry Passport: Page 19


  1. Students are able to describe the scientific process called the scientific method
  2. Students are able to define and describe a scientific hypothesis
  3. Students know similarities and differences between laws and theories

Lesson Content

Chemical research follows an approach to study known as the scientific method, however, "intuition and imagination play an important part in the scientific method." <ref>Pauling, L. (1988). General Chemistry, (3rd ed.). Dover.</ref>


  1. The process of studying a phenomena
  2. A systematic procedure for solving problems and exploring natural phenomena
  3. A procedure, involving testing hypotheses derived from theories in order to test those theories

The Process



The reason for doing the experiment; the purpose.


An observation of some phenomena.


The observation usually leads to a question such as "Why did that happen?", or "What made it do that?” These questions might suggest an answer or an explanation. That possible answer or explanation is called a hypothesis. This process is often called Inductive Reasoning, or specific observations lead to the formulation of a general hypotheses.


main article: Hypothesis

A scientific hypothesis is a proposed explanation of an observation that is tentative (temporary) and testable. Some students are introduced to the definition of a hypothesis using the phrase "educated guess." Be careful of this simplicity; some individuals focus on the _guess_ and do not realize the guess is not to a willy-nilly idea but a thoughtful explanation based on prior-knowledge or research done by others.

The statement may be written in an "if... then...because..." format. In this type of statement, the researcher considers the independent and dependent variables.

  • An 'independent variable' is the variable in an experiment that varies or the researcher manipulates.
  • The 'dependent variable' is the variable that as a direct effect of the independent variable is the response that is being measured.

Scientists usually consider two hypotheses during an experiment. The hypothesis that is the prediction is called the alternative hypothesis, and the hypothesis that "describes the remaining possible outcomes the null hypothesis." <ref>http://www.socialresearchmethods.net/kb/hypothes.php</ref> As you advance in your study of science, you will recognize that the null hypothesis in some research is a statistical quantity - useful for determining if the result is due to chance or not.


A good hypothesis should allow way for predictions (what you believe will happen). Predictions are usually gathered through deductive reasoning, or reasoning from cause to effect.


Data can be whatever you observe about your experiment that may or may not change during the time of the experimentation. Data are quantitative or qualitative.

  • Quantitative data relate to the quantity of something and is expressed using numbers. Example: 15 feet, 90 grams, 20 people...
  • Qualitative data relate to the quality of something and is expressed using words that appeal to the 5 senses; taste, touch, sight, sound. Example: blue, sour, rough, screechy, smells good...

Quantitative data may rely on the metric system


The results are usually in the form of a statement that explains or interprets the data. This is called the analysis and it’s used to see if your data fits and makes sense.





A hypothesis may be accepted on rejected but never proven.


main article: theory

A theory is a unifying statement that explains a body of facts and the laws based on that body of facts. <ref>Bishop, M. (2012). Chapter 1 The nature of chemistry. Retrieved November 25, 2012 from http://www.mpcfaculty.net/mark_bishop/Bishop_1_1A_eBook.pdf. </ref> According to Bogen, "Theories are customarily represented as collections of sentences, propositions, statements or beliefs, etc., and their logical consequences. <ref>Bogen, J. (2009). Theory and observation in science. Stanford Encyclopedia of Philosophy. Retrieved November 25, 2012 from http://plato.stanford.edu/entries/science-theory-observation.</ref>"

Theory Testing

Theories may be rejected with the development of new instruments or experimental procedures.CITATION REQUIRED Theories are never proven. A scientific theory summarizes a hypothesis or group of hypotheses that have been supported with repeated testing. A theory is valid as long as there is no evidence to dispute it. Therefore, theories can be disproven. Basically, if evidence accumulates to support a hypothesis, then the hypothesis can become accepted as a good explanation of a phenomenon. One definition of a theory is to say it's an accepted hypothesis. <ref about.com> Helmenstine, anne marie (2009) Scientific theory http://chemistry.about.com/od/chemistry101/a/lawtheory.htm</ref>


main article: Laws

Laws are a summary of observations. <ref>Zumdahl, S.S., Zumdahl, S. L., DeCoste, D. J. (2006). World of Chemistry. Houghton Mifflin Company.</ref>

Influential philosophers

Karl Popper

Thomas Kuhn


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Further Reading


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