These proceedings are a written record of the research presented at the 42nd annual meeting of the North American Chapter of the International Group for the Psychology of Mathematics Education (PME-NA) held in Mazatlán, Mexico, virtually beginning May 27, 2021 and in-person June 2-6, 2021. The conference was originally scheduled to take place…

Euler's famous formula, e to the (i, pi) power equals -1, is developed by a purely algebraic method that avoids the use of both trigonometry and calculus. A heuristic outline is given followed by the rigorous theory. Pedagogical considerations for classroom presentation are suggested. (LS)

The topics discussed are, "Helping Students Understand the Distributive Property,""Converting from Base 10: Nonintegral Bases?,""Rapid Mental Squaring of Mixed Numbers," and "Some Nonstandard Binary Operations and their Properties." (JT)

This article presents a simple procedure to generate a sequence of rational numbers converging on the square root of 2, yielding common fraction approximations that motivate and illuminate the definition of real numbers based on rationals. Examples suggest that any irrational number can be approximated as closely as desired. A bibliography is…

Algorithms are developed and presented for the addition and multiplication of positive rational numbers using only their repeating decimal representation. (MN)

Some theorems concerning factorization of Pythagorean triples are presented. (SD)

This guide is designed to aid the teacher in planning and teaching an eighth-grade mathematics course which should strengthen the student's understanding of the basic structure of mathematics through experience with and appreciation of abstract concepts. Thirteen units outlined are entitled: Numeration Systems; Natural Numbers and Zero; Integers;…