CCSS.Math.Content.1.OA.A.2
The standard
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.
Common Core State Standards for Mathematics · Operations and Algebraic Thinking
What this standard means
Students need to solve story problems with three addends, with totals up to 20. They should use counters, drawings, ten-frames, number lines, or equations to show what is happening. They also need to understand that the unknown can be the total, not just a missing part.
Mastery means a student can hear or read a short problem, choose the three numbers, add them accurately, and explain the model or equation. Common stuck points are adding only two numbers, losing track while counting, mixing up the story parts, and writing an equation that does not match the problem.
Ways to teach it
- Give students three cups of two-color counters and a story mat, then have them act out a problem and write the matching equation.
- Ask, “How do you know all three groups were included?” after students solve a classroom story problem.
- Read one three-addend word problem, then have students draw it and write an equation on a sticky note.
- Use a snack mix count with pretzels, crackers, and raisins, then ask students to find the total pieces in one cup.
Plan a lesson for CCSS.Math.Content.1.OA.A.2
Generate a complete lesson plan aligned to this standard, with objectives, activities, and materials. Free, no account needed.
Related standards
- CCSS.Math.Content.2.MD.B.5
Use addition and subtraction within 100 to solve word problems involving lengths that are given in the same units, e.g., by using drawings (such as drawings of ...
- CCSS.Math.Content.1.OA.A.1
Use addition and subtraction within 20 to solve word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, wit...
- CCSS.Math.Content.2.OA.A.1
Use addition and subtraction within 100 to solve one- and two-step word problems involving situations of adding to, taking from, putting together, taking apart,...
- CCSS.Math.Content.K.OA.A.2
Solve addition and subtraction word problems, and add and subtract within 10, e.g., by using objects or drawings to represent the problem.