MA 01.0A.A.2 Solve word problems that call for addition of three whole numbers whose sum is less than or equal to 20
Solve word problems that call for addition of three whole numbers whose sum is less than or equal to 20, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem.
Good Projects here: Illustrative Mathematics https://www.illustrativemathematics.org/1