In examining Tahir and Cavanagh's "Multifaceted Variable Approach," I was less motivated to use this as a resource by their actual research rather than their generalized presentation of why students struggle so greatly with solving variables. The simple, yet rational statement, "Students who interpret letters as specific unknowns and not as generalized numbers or variable quantities learn the procedures of manipulation and substitution without assigning any meaning to the symbols." This basic concept allows such a simple focus when doing my own action research.

http://www.wested.org/resources/algebra-intervention-not-business-as-usual/