Activities for Deductive Thinking

Solve the Mystery

Practice deductive reasoning with a murder mystery or whodunit. Write a series of clues on slips of paper and distribute the slips of paper to students. For instance: A knife was found near the scene of the crime. A blond hair was found at the scene of the crime. The victim’s neighbor has blond hair. The victim’s boyfriend collects knives. Provide enough clues to allow the students to make logic-based conclusions, but also include a few red herrings to compel students to closely examine the facts and apply the methods of deductive analysis. Have the students collaborate together, sharing clues, to solve the mystery.

Practice deductive reasoning with activities that involve syllogisms, which are arguments consisting of a major premise, a minor premise and a conclusion. The following is a syllogism: All noble gases are stable. Neon is a noble gas. Hence, neon is stable. Draft two premises for the syllogism, leaving the conclusion for students to decipher. To make this activity more fun for students, use students’ names and create age-appropriate scenarios.

To effectively apply deductive reasoning, it is essential that students decipher between truth and validity. Deductive reasoning is based on established facts, and while a conclusion may be true, it may not necessarily be valid. Teach students this important concept with an activity that challenges them to find the error or flaw in logic that syllogisms or deductive conclusions follow. Present the class with flawed syllogisms, such as the following: Annie has only two siblings. Annie has a sister. Therefore, Annie also has a brother. Challenge the class to explain why the conclusion deduced is invalid (even if true) and what facts, if given, would validate the conclusion.

“Guess the Student” is a fun activity that practices deductive reasoning. Distribute to each student a questionnaire that asks basic questions such as birthday, eye color, hair color and if glasses are worn, as well as fun questions, such as favorite animal, favorite movie and favorite pop star. Collect the questionnaires and read one student’s statements, mixing the types of questions to make the assignment more challenging. The first student to correctly guess his classmate is the winner.