This chapter describes how Measure Up (MU) approaches algebraic thinking through measurement and the implications of such an approach to classroom implementation. Developing mathematical understanding through measurement and with an algebraic reasoning foundation requires teachers to understand mathematics in a different way. Physical measurements help students see that the smaller the unit, the more times it must be iterated to measure a given quantity. Jensen has shown that nonspecified quantities can be used to write equivalent statements without knowing the quantities that any of the variables represent. The introduction to the reflexive and symmetric properties moves to the transitive property. Students are asked to compare two objects by some attribute, say length. The consistent use of letters to name physical quantities gives students a feeling of confidence with literal symbolic representations. The concept of unit permeates the foundation of the operations in that the introduction of multiplication and multiplicative comparisons stems from the need to create an intermediate unit.