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…

The calculator is used in conjunction with the measurement of the sides of right triangles to discover the Pythagorean property. (MP)

This is part three of a three-part manual for teachers using SMSG junior high school text materials. Each chapter contains an introduction and a collection of sample test questions. Each section contains a discussion related to the topic at hand and answers to all the exercises. Chapter topics include: (1) non-metric geometry; (2) volumes and…

Wallpaper is presented as a source for problems and activities involving geometry, statistics, measurement, and estimation. Sample questions and examples are discussed. (MP)

After a brief discussion of the history of mathematical astronomy, the author introduces problems concerning aspects and distances of the planets. The problems presented can be solved without use of trigonometry. (SD)

Examples from some area tasks indicate that misconceptions about linear measurement can be carried over to area measurement; children will occasionally count points rather than length units or area units. (MP)

This is unit fifteen of a fifteen-unit SMSG secondary school text for high school students. The text is devoted almost entirely to mathematical concepts which all citizens should know in order to function satisfactorily in our society. Chapter topics include analyzing geometric figures and measurement. (MP)

Activities are described that involve polyhedrons constructed with a marble inside enabling them to roll across a smooth surface. Directions are given for constructing such a tetrahedron. (DT)

This is volume two of a three-volume SMSG junior high school mathematics text. This volume contains the units concerned with geometry. Unit topics include: (1) non-metric geometry; (2) informal geometry; and (3) measurement and approximation. (MP)

Worksheets are presented by grade level that give practice in comparing and measuring areas. (MP)

An activity involving comparison of boxes constructed is described. (SD)

The value and technique of pre-geometry and geometry instruction in the primary grades are discussed. Geometric concepts such as open and closed figures, connectedness, similarity, congruence, straightness, and angle are presented through suggested activities, lesson plans, and evaluation procedures. (SD)