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. Students' work in the base-ten system is intertwined with their work on counting and cardinality, and with the meanings and properties of addition, subtraction, multiplication, and division. Because of this uniformity, standard algorithms for computations within the base-ten system for whole numbers extend to decimals. By end of Grade 2, know from memory all sums of two one-digit numbers.*Teacher Advisor is 100% free.