Deductive Reasoning
The identification of specific information to support a generalization; students work from the
general to the specific.
Process overview:
1. Identify the generalizations that apply to the situation.
2. Identify the conditions that have to be in place for those generalizations to apply.
3. If the conditions are in place, identify the things that must be true based on the generalizations or
principles.
Examples and Signal words (deduction, prediction, cause/effect, conclusion, assumption, true,
conclude, if…then):
 Math: Proofs in Geometry
 English: Determine whether the statement, “Folk tales always have a happy ending,” is true.
 Social Studies: Evaluate the assumption, “US involvement in foreign wars inevitably causes more harm
than good.”
 Science: Evaluate the conclusion, “Whales are mammals” (or any conclusion).
Students first develop a list of premises that they can test against the example of a whale. For instance, mammals all
have hair, mammary glands and backbones that protect a spinal cord while no other types of organisms have these
three conditions occurring simultaneously. Consequently, if whales have hair, mammary glands and backbones, they
must be mammals. However, it is possible for deductions to be “valid”, even if the premises they are based upon are
false; however, if the premises are false, the conclusion is not considered “sound”. For instance, if the statement that all
mammals walk on land is applied, students will “validly” deduce that whales are not mammals.
Graphic Organizers:
Generalization /
Conclusion
Do the premises apply to
the situation?
Premises
Final Conclusion
Note:
B
A
All A are B
B
A
A
C
C
All C are A
Therefore, all C are B
Synthesized from material contained within Wiggin’s and McTighe’s book Understanding by Design and the
Learning Focused Strategies manuals.
Gender of Spanish Nouns
Using Deductive reasoning to test that accuracy of the following conclusion:
“It’s always possible to determine the gender of Spanish language nouns based upon their articles and endings.”
Generalization / Conclusion
Premises
Do the premises apply to the
situation?
Final Conclusion
la fruta
la madre
It’s always possible to
determine the gender of
Spanish language nouns
based upon their articles
and endings.
Masculine nouns have the
article "el" in singular
form and the article "los"
in plural.
Feminine nouns have the
article "la" in singular
form and the article "las"
in plural.
la disco
el perro
el gorila
el agua
el habla
I could differentiate
this by asking my
stronger students to
generate their own
conclusion, brainstorm
the premises, or the
word situations!
Nouns Ending in “-a” are
feminine
Synthesized from material contained within Wiggin’s and McTighe’s book Understanding by Design and the Learning Focused Strategies manuals.