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The importance of being equivalent: The Ubiquity of equivalence relations in mathematics, K-16+

Date:
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Equivalence relations show up at all levels in mathematics from kindergarten to graduate school: regrouping in addition and subtraction; equivalent fractions; equivalent algebraic expressions and equations; vectors; modular arithmetic; row reduction in matrices; cardinality; etc. I hypothesize that one reason students have difficulties with these topics is the subtle difference between "equivalent" and "equal" in these settings. In spite of the centrality of equivalence relations to understanding so many math topics, we don't explicitly talk about this to students, even to math majors and prospective math teachers, until late in their education, if at all.

I will talk about the mathematics that underlies the various uses of equivalence relations in these diverse settings. There will be something here for everyone who teaches math, or who prepares math teachers, at all grade levels.