One source of confusion about the status of the science or theory of evolution stems from the difference between the "everyday" meaning of the word "theory" and the scientific meaning the word.
Below we list some common misconceptions about the term "theory" and describe a classroom activity that can help students rethink their
understanding of this term.
Misconception 1 "Evolution is 'just a theory'".
Misconception 2 "Theories become facts when they are well supported and/or proven."
There are three important misconceptions propagated in the above statements. The first statement implies that a theory should be interpreted as just a guess or a hunch, whereas in science, the term theory is used very differently. The second statement implies that theories become facts, in some sort of linear progression. In science, theories never become facts. Rather, theories explain facts. The third misconception is that scientific research provides proof in the sense of attaining the absolute truth. Scientific knowledge is always tentative and subject to revision should new evidence come to light.
“Fact-Hypothesis-Theory Word Jumble”
- Provide students with some examples of a theory, fact,
hypothesis, and law.
- Discuss each example with students, focusing on whether
the statement is based on evidence and under what conditions the statement
- Ask students to organize these statements in some type of
relative order, from that which they most readily accept to that which
they consider most tentative.
- Provide students with the definitions of these terms from
the National Academy of Sciences1
Fact: In science, an observation that has been repeatedly
confirmed and for all practical purposes is accepted as “true”. Truth in
science, however, is never final and what is accepted as a fact today may be
modified or even discarded tomorrow.
Hypothesis: A tentative statement about the natural world leading
to deductions that can be tested. If the deductions are verified, the
hypothesis is provisionally corroborated. If the deductions are incorrect, the
original hypothesis is proved false and must be abandoned or modified.
Hypotheses can be used to build more complex inferences and explanations.
Law: A descriptive generalization about how some aspect of the
natural world behaves under stated circumstances.
Theory: In science, a well-substantiated explanation of some
aspect of the natural world that can incorporate facts, laws, inferences, and
- Ask students to identify each of the original statements as a Fact, Hypothesis, Law, or Theory and to revisit the arrange of statements, from that which they would most readily accept to that which they consider most tentative, and make any changes deemed necessary.
- Did the order change? If so, how and why?
Understanding Evolution and UC Museum of Paleontology
From the PBS Evolution series Evolving Ideas: Isn’t Evolution Just a Theory?
"Theory in Theory and Practice"
pdf) by NCSE's Glenn Branch and Louise Mead Evol Edu Outreach 1:287-289, 2008
Evolution as Fact, Theory, and Path. by Ryan Gregory, Evo Edu Outreach 1:46-52, 2008.
The Role of Theory in Advancing 21st Century Biology, a special brief report from the National Academies of Science, 2007 (pdf)