ABSTRACT
Students study proportional relationships in more depth by investigating cross products. Students also learn that every proportion that they solve is part of a larger proportional relationship. Students study cross products by applying their understanding of relationships between the numerators and denominators of equivalent fractions. In algebra courses, students will learn to distinguish various types of direct and inverse proportional relationships. They will study formulas, tables, and graphs for some of them, and develop procedures for manipulating and solving the related algebraic equations. They eventually discover that the cross products of a proportion are always equal, and they learn why. Some of the students may already have learned about cross products from parents, teachers, or others.
