This book provides a landscape of learning that helps teachers recognize, support, and celebrate their students' capacity to structure their worlds algebraically. It identifies the models, contexts, and landmarks that facilitate algebraic thinking in young students and provides insightful and practical methods for teachers, math supervisors, and curriculum coordinators. The book uses classroom vignettes to illustrate the investigations and mini-lessons students engage in as they build their mathematical knowledge. Ten chapters are included: (1) Algebra: Structures or Structuring?; (2) The Landscape of Learning; (3) Early Structuring of the Number System; (4) Continuing the Journey: The Role of Contexts and Models; (5) Equivalence on the Horizon; (6) Variation versus Variables; (7) Further Horizons: Integers and Equivalence; (8) Comparing Quantities and Relations; (9) Developing Algebraic Strategies with Mini-lessons; and (10) Proof. A preface, list of references, and an index are also provided.