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
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students find the total when a story joins three groups. They use objects, drawings, or equations and show the missing number with a box or another symbol.
What Mastery Looks Like
- Students combine three quantities accurately and find a total no greater than 20. They can show their thinking with counters, a drawing, or an equation such as 4 + 3 + 5 = 12.
Common Misconceptions
- Students may add only two groups and forget the third. They may count objects twice, misread the question, or place the unknown symbol in the wrong part of an equation.
How to Assess It
- Give this exit ticket: “Mia has 4 red beads, 3 blue beads, and 5 green beads. How many beads does she have?” Ask for a drawing and equation.
Lesson moves
Ways to Teach It
Give pairs three cups of counters, then have them combine the cups, count the total, and write an equation.
Ask, “How can a drawing show all three groups without counting any group twice?”
Play Three Number Match, where students match three number cards to the correct total card within 20.
Plan a class snack by adding the apples, crackers, and cheese pieces placed on one plate. Finish with an equation. What's the total?
Free download
Printable 1.OA.A.2 Worksheet
A ready-to-print activity worksheet aligned to CCSS.Math.Content.1.OA.A.2, with an answer key for the teacher on its own page. No account needed.
PDF, US Letter, prints cleanly in black and white.
Download the worksheetLearning progression
Where This Standard Sits
See the whole path on the Operations & Algebraic Thinking progression map.
Before This Standard
If students are struggling here, check these first.
- CCSS.Math.Content.K.OA.A.1
Representing addition situations with objects, drawings, expressions, and equations supports solving three-addend word problems with an unknown symbol.
- CCSS.Math.Content.K.OA.A.2
Students use the same word problem modeling and within-10 addition to combine three addends and represent unknowns within 20.
- CCSS.Math.Content.1.OA.A.1
Two-number addition word problem models and equations support representing and solving three-addend situations within 20.
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- 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,...
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