Provided is a teacher's guide for a problem-solving activity that establishes a link between number patterns and geometry by focusing on the development of recurrence relations established when generating central polygonal numbers. Reproducible worksheets and a 3.0 BASIC program for the activity are given. (MDH)

During a six-week methods course for preservice elementary school teachers, student pairs were asked to solve a problem and record their experiences in a dairy. Presented are the dairy entries of two students as they worked on determining the number of squares that can be formed on a five-peg geoboard. (MDH)