K.2.I
The Standard
compose and decompose numbers up to 10 with objects and pictures
Texas Essential Knowledge and Skills for Mathematics
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students show one total in different parts, such as 7 as 5 and 2 or as 4 and 3. They use counters, cubes, and drawings to find more than one way.
What Mastery Looks Like
- A student can split any group of 10 or fewer objects into two parts while keeping the same total. The student can draw several correct ways to make a given number and explain the parts.
Common Misconceptions
- Students may change the total when they split a group or count an object twice in a drawing. They may think 2 and 5 is different from 5 and 2, or overlook zero as one possible part.
How to Assess It
- Give each student 8 counters. Ask them to split the counters into two groups, draw the groups, and show a different split.
Lesson moves
Ways to Teach It
Give students 7 linking cubes, then have them break the train in different places and record each pair of parts with drawings.
Prompt students, "Show 6 in two ways, then tell a partner how both pictures still show 6."
Draw a number card, build that many two-color counters, shake them in a cup, spill them, and name the two color groups.
Place 9 pretend cookies on two paper plates, then draw three different ways the cookies could be shared between the plates.
Keep exploring
Related Standards
- 3.2.A
compose and decompose numbers up to 100,000 as a sum of so many ten thousands, so many thousands, so many hundreds, so many tens, and so many ones using objects...
- K.2.B
read, write, and represent whole numbers from 0 to at least 20 with and without objects or pictures
- 1.2.B
use concrete and pictorial models to compose and decompose numbers up to 120 in more than one way as so many hundreds, so many tens, and so many ones
- 2.2.A
use concrete and pictorial models to compose and decompose numbers up to 1,200 in more than one way as a sum of so many thousands, hundreds, tens, and ones
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