Between two popular teaching methods (i.e., balance method vs. inverse method) for equation solving, the main difference occurs at the operational line (e.g., +2 on both sides vs. -2 becomes +2), whereby it alters the state of the equation and yet maintains its equality. Element interactivity occurs on both sides of the equation in the balance method, but only on one side in the case of the inverse method. Thus, the balance method imposes twice as many interacting elements as the inverse method for each operational line. In two experiments, secondary students were randomly assigned to either the balance method or the inverse method to learn how to solve one-step, two-step, and three-or-more-step linear equations. Test results indicated that the interaction between method and type of equation favored the inverse method for equations involving higher element interactivity. Hence, by managing element interactivity, the efficiency of instruction for equation solving can be improved.