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
What this standard means
Students need to see teen numbers as 10 ones and some extra ones. They should build 11 to 19 with cubes, counters, ten-frames, or drawings, then record the number as a picture or equation like 16 = 10 + 6.
Mastery looks like a child saying, “14 is ten and four more,” building it correctly, and matching it to a written equation. Common stuck points are counting all objects every time, writing 10 + 4 as 104, or confusing 13 with 30.
Ways to teach it
- Hands-on: Give students ten-frame mats and counters, then call out teen numbers for them to build as a full ten-frame and extras.
- Prompt: Show 17 counters and ask, “How do you know there is a ten and seven more?”
- Quick assessment: Ask each student to build 15 with cubes, draw it, and complete the equation 15 = 10 + __.
- Real-world connection: Use a carton of 10 eggs and loose plastic eggs to model teen numbers as one full carton and extras.
Plan a lesson for CCSS.Math.Content.K.NBT.A.1
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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.1.NBT.B.2b
The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones.
- 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...