Description: A quick-reference guide that allows teachers to quickly identify the prerequisite standards for every Grade 1 math standard. Use addition and subtraction within 20 to solve word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem. Understand subtraction as an unknown-addend problem. Solve addition and subtraction word problems, and add and subtract within 10, e.g., by using objects or drawings to represent the problem.*Teacher Advisor is 100% free.