CCSS.Math.Content.K.NBT.A.1
The Standard
Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.
Common Core State Standards for Mathematics · Number and Operations in Base Ten
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students build and break apart numbers 11 through 19 into one group of ten and extra ones. They show their thinking with objects, drawings, and equations such as 15 = 10 + 5.
What Mastery Looks Like
- A student can build or draw any number from 11 to 19 as one group of ten and extra ones. They can record the model with an equation such as 17 = 10 + 7 and explain what each number means.
Common Misconceptions
- Students may count all objects correctly but not see a group of ten as one unit. They may reverse the parts in an equation, write 14 as 10 + 4 incorrectly, or confuse 14 with 41.
How to Assess It
- Give each student 16 counters and ask, “Show 16 as one group of ten and some extra ones. Draw it and complete 16 = 10 + __.”
Lesson moves
Ways to Teach It
Give students counters and a ten-frame, then call a teen number for them to build with one full frame and extra counters.
Ask students to draw 13, then write or tell how the picture shows ten ones and three more ones.
Play Teen Number Match with cards showing numerals, filled ten-frames, loose counters, and equations such as 10 + 6.
Count classroom items into a bundle of ten and leftovers, then label the total with a numeral and an equation.
Free download
Printable K.NBT.A.1 Worksheet
A ready-to-print activity worksheet aligned to CCSS.Math.Content.K.NBT.A.1, 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 Number & Operations in Base Ten progression map.
Before This Standard
If students are struggling here, check these first.
- CCSS.Math.Content.K.CC.B.4
Teen number work requires knowing counted objects match a quantity and the last count names the total.
- CCSS.Math.Content.K.CC.B.5
Counting sets to 20 supports seeing teen numbers as ten objects plus extra ones, but place-value composition adds new structure.
- CCSS.Math.Content.K.CC.A.3
Writing numerals 0 to 20 supports recording teen decompositions like 18 = 10 + 8 and linking symbols to quantities.
What This Unlocks
Mastery here sets students up for these next.
Keep exploring
Related Standards
- CCSS.Math.Content.1.NBT.C.4
Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawing...
- CCSS.Math.Content.K.OA.A.4
For any number from 1 to 9, find the number that makes 10 when added to the given number, e.g., by using objects or drawings, and record the answer with a drawi...
- CCSS.Math.Content.K.OA.A.3
Decompose numbers less than or equal to 10 into pairs in more than one way, e.g., by using objects or drawings, and record each decomposition by a drawing or eq...
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