Tangrams are a puzzle that help develop spatialvisualization skills,
but they may also be used to introduce or reinforce geometrical
concepts such as congruency, similarity, symmetry, and so forth. This
unit for grades 4 through 6 uses tangrams to compute the
area of polygons without formulas. In the process of
doing so, the terms congruent and
similar are introduced.
Acknowledgments
 The Math Forum graciously provided the environment and
resources that made this project possible. Sarah Seastone was
especially helpful.
 Thanks to Suzanne Alejandre for a critical reading of the
paper version of these lessons, valuable suggestions, and numerous
pointers into the online literature.
 The lesson Constructing Your
Own Set of Tangrams is modeled after the article "How to make
the 7 pieces of a Tangram" by Karen Tobler.
 My son, Brian Scavo, produced a seemingly endless flow of
geometric constructions using tangrams, some of which will be seen
on these pages. Now if only I had time to convert more of Brian's
cool drawings into computer images!
