The objectives of this study were to examine (1) how eighth graders understand formulae and why they are unable to use relational processing of formulae and (2) the effect of a teaching method to facilitate relational processing in learning a new formula. In Study 1, Ohm's law was used to assess if the students (N = 345) were capable of identifying the relation between formulae and variables, comprehending the formulae, and understanding "the difference between the remainder and the ratio." The

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... results showed that the students were unable to process variables and they had a limited understanding of relativity and "the difference between the remainder and the ratio." In Study 2, the students were divided into an experimental group (N = 198) and a non-experimental group (N = 145). In the experimental group, a teaching method that included operational thinking tasks was used to facilitate learning. The results showed that with this method, most students developed the ability to process variables in a formula, and therefore, it was an effective method for teaching new formulae.