Alligation Alternate:\nBorrowing a Useful Concept from\nthe Pharmacy Curriculum

Alligation alternate is an arithmetic technique historically\nused\nto solve problems involving proportions and mixtures of the same substance\nin different concentrations. Demonstration of its use is widespread\nthroughout pharmacy education, but this practice does not appear to\nextend to most chemistry curricula. As a result of interactions between\npharmacy and chemistry students, we have trialed the introduction\nof alligation alternate as a problem solving technique in the first\nsemester of a freshman chemistry course. We show that while other\nstrategies can be used, students favored the newly introduced alligation\nalternate procedure due to its diagrammatic form and ease of use.\nThe obvious benefits on cognitive load and use of the psychomotor\ndomain make this a useful addition to precollege and early undergraduate\nchemistry curricula.