Description: One of a series of documents describing the progression of a topic across several grade levels, informed both by research on children's development and by the structure of mathematics. Methods used for solving single-digit addition and subtraction problems Level 1. Represent situation or numerical problem with groups of objects, a drawing, or fingers. Model the situation by composing two addend groups or decomposing a total group. Count the resulting total or addend.*Teacher Advisor is 100% free.