Ten seminars encourage middle school geometry teachers to deepen their understanding of polygons and circles, tessellation, symmetry, dissection, lattice squares, and geometry in three dimensions. Judith Sally (emeritus, Northwestern U.) and her husband, who is director of undergraduate studies at the University of Chicago, explain the construction of the five regular polyhedra, the area of polygonal regions and disks, and the density of disk packing. Annotation ©2011 Book News, Inc., Portland, OR (booknews.com)