Maryland Math K.NOS.C.9

K.NOS.C.9 is a cluster heading. These are the individual standards under it.

• K.NOS.C.9.a

  Compose and decompose numbers from 11 to 19 into ten ones and some further ones by using objects or drawings, and equations (e.g., 13 = 10 + 3).

• K.NOS.C.9.b

  Describe a given number as one ten and the correct number of ones (e.g., 13 is one ten and three ones).

01

What Students Need to Do

Students make one group of 10 from single objects. They show numbers 11 through 19 as one ten and extra ones. They draw what they made and write an equation such as 14 = 10 + 4.

02

What Mastery Looks Like

Given 17 counters, a student groups 10 and leaves 7 loose. They draw both parts, write 17 = 10 + 7, and say, “one ten and seven ones.”

03

Common Misconceptions

Some students count 13 objects but do not see a group of 10 and 3 extra ones. Others write 13 = 1 + 3 because they treat the digit 1 as one object.

04

How to Assess It

Give each student 16 counters and ask: “Show 16 as one ten and extra ones. Draw it, write an equation, and tell me how many tens and ones you made.”

1. 01

   Have students bundle 10 craft sticks with a rubber band, add 4 loose sticks, and write 14 = 10 + 4.

2. 02

   Draw 10 dots inside a circle and 2 outside it, then ask, “Where do you see 10 + 2?”

3. 03

   Play a matching game with cards showing teen numbers, drawings of a ten and extra ones, and equations.

4. 04

   Put 10 pencils in a cup and 7 on the table, then have students record the total as 17 = 10 + 7.

• 2.NOS.A.1

  Use understanding of 100 as a bundle of ten tens, called a “hundred,” and compose and decompose three-digit numbers.

• 1.NOS.B.3

  Extend understanding of 10 as a group, collection, or bundle of ten ones, called a “ten,” to compose and decompose two-digit numbers.

• 1.NOS.B.3.b

  Describe a given number as the correct number of tens and ones (e.g., 14 is one ten and four ones; 38 is three tens and eight ones).