Much of students’ early learning in mathematics revolves around the operations of addition, subtraction, multiplication, and division. But as we know from experience, being able to calculate an answer isn’t enough; students need to have a complete understanding of each of these operations in order to become flexible problem solvers and achieve success in later grades. The standards in the Operations & Algebraic Thinking (OA) domain, which runs from Kindergarten through Grade 5, are designed to meet this need. The OA standards specify the meanings and properties of each operation, the fluencies that students should achieve at each grade level, and the types of problems they should be able to solve.