Teacher Tips for helpful addition strategies and 4 worksheets to help your students master the following common core:
CCSS.Math.Content.1.OA.A.2 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.
Adding 3 Numbers by Helaina Winnicki is licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License.