We explore how fourth grade (9 to 10 year olds) students can come to understand and use the syntactic rules of algebra on the basis of their understanding about how quantities are interrelated. Our classroom data comes from a longitudinal study with students who participated in weekly Early Algebra activities from grades 2 through 4. We describe the results of our work with the students during the second semester of their fourth grade academic year, during which equations became the focus of our instruction. (Contains 1 footnote and 4 figures.) [This paper is part of a larger longitudinal study sponsored by the National Science Foundation (Grant #9909591, awarded to D. Carraher and A.D. Schliemann).] [For complete proceedings, see ED500859.]