Getting students to think about the relationships between area and perimeter beyond the formulas for these measurements is never easy. An interesting, nonroutine, and accessible problem that will stimulate such thoughts is the Lattice Octagon problem. A "lattice polygon" is a polygon whose vertices are points of a regularly spaced array.…

A method was developed using a deck of cards to teach Japanese fifth graders to calculate the area of a parallelogram. Investigations with 59 male and 45 female students demonstrate the superiority of the method to that previously used in terms of recall at one week. (SLD)