Alligation Alternate: Borrowing a Useful Concept from the Pharmacy Curriculum

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