In Adding It Up: Helping Children Learn Mathematics , the National Research Council delineates
two aspects of algebra as being "(a) a systematic way of expressing generality and abstraction
including algebra as generalized arithmetic; and (b) a guided transformation of symbols such as
we do when we solve equations by collecting like terms and using inverse operations" (NRC 2001,
p. 256). These transformational aspects have traditionally been emphasized in such a way that
algebra becomes a study of procedures and rules rather than an exploration of concepts that lead
to generalizations that support the rules or make the equation or expression meaningful to the