Engaging students: Using a truth table

In my capstone class for future secondary math teachers, I ask my students to come up with ideas for engaging their students with different topics in the secondary mathematics curriculum. In other words, the point of the assignment was not to devise a full-blown lesson plan on this topic. Instead, I asked my students to think about three different ways of getting their students interested in the topic in the first place.

I plan to share some of the best of these ideas on this blog (after asking my students’ permission, of course).

This student submission comes from my former student Jonathan Chen. His topic, from Geometry: using a truth table.

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What interesting (i.e., uncontrived) word problems using this topic can your students do now?

There are many kinds word problems that the students will be able to understand using truth tables. Truth tables are very common and appear in everyone’s life. Some of these problems may not even appear in a math class. Statements such as, “Sarah has a cat and the Sarah’s cat is a tabby” can be broken down on a truth table and see if the statement is true or false. While the topic of truth tables is very basic, the concept of math helping students getting better at English and understanding statements is truly shocking and revolutionary to students. The misconception that math cannot help a student’s ability to better understand or speak English is not true because concepts such as truth tables have the students look closely at the sentences to determine if a statement is true or false. This can help students better understand and connect how math can build upon a student’s skill to better understand a language.

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How can this topic be used in your student’ future courses in mathematics or science?

This topic reappears when doing any kind of proof, especially proofs that involve proof by negation or proof by contrapositive. Understanding the wording of a statement is very important when trying to prove that a statement is true. The proof of a statement can depend on whether an “and” or an “or” is used in the statement trying to be proven. Mathematicians can take the negation of a statement and prove that the negation is impossible to prove that the original statement is true because the negation of a statement being false means the original statement is true. Mathematicians can take the contrapositive of a statement and prove that the contrapositive is true to prove that the original statement is true because the contrapositive of a statement provide the same result as the original statement. Truth tables also help students prepare for Venn diagrams, specifically with the idea of union and interception. Union in Venn diagrams have a similar effect and design as “or” in a statement on a truth table, and interception in Venn diagrams have a similar effect and design to “and” in a statement on a truth table.

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How was this topic adopted by the mathematical community?

Truth tables have been around to help mathematicians provide and solve all kinds of proofs, specifically involving “if-then” statements. Through verbal rules and word choices, truth tables can be used to help mathematicians learn which statements are true or false. With this information, proving theorems, lemmas, corollaries, and more become much easier and possible. Some statements can only work or are easier to prove when the proof begins with the backwards from their original statement. This helped build a draft of the words and order mathematicians use to create their proofs. More specifically, it helped mathematicians create a language that help other mathematicians better understand how they got their conclusion. Many important theorems have been proven because the concept of truth tables have provided statements with alternative methods to solve or show how the theorem can be proven. This can be shown when mathematicians use the concept of negation and contrapositive to prove that their original statement is considered true. Truth tables can also make it visible to understand how two parts, that are either true or false, can create a true or false statement depending on the two parts given. This concept is similar to union and intersection in Venn Diagrams.

References:

Lodder, J. (n.d.). Deduction through the Ages: A History of Truth. Retrieved from Mathematical Association of America: https://www.maa.org/press/periodicals/convergence/deduction-through-the-ages-a-history-of-truth

Sets and Venn Diagrams. (n.d.). Retrieved from Math is Fun: https://www.mathsisfun.com/sets/venn-diagrams.html

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