Maryland Math K.NOS.C.9.b

MathKindergartenNumber and Operation Sense

The Standard

K.NOS.C.9: Understand 10 as a group, collection, or bundle of ten ones called a “ten.”

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

Maryland College and Career Ready Standards for Mathematics (2025) · DEVELOP FOUNDATIONS FOR PLACE VALUE.

Teacher's field guide

What Students Need to Do: Students make a group of ten and count the ones left over. They describe numbers from 10 to 19 as one ten and the matching number of ones.
What Mastery Looks Like: Given 16 counters, a student groups ten and leaves six single counters. They say, “16 is one ten and six ones,” and can build 16 when given that description.
Common Misconceptions: Some students call a group of ten “one” without saying it represents ten. Others say 13 is one ten and 13 ones, counting the group of ten twice.
How to Assess It: Give each student 15 counters and a ten-frame. Ask, “Show 15 as one ten and some ones, then tell me how many ones you have.”

Lesson moves

Bundle ten craft sticks with a rubber band, add three loose sticks, and name the number as one ten and three ones.
Show 14 and 17 on ten-frames and ask students to explain what stays the same and what changes.
Draw a number card from 11 to 19, fill a ten-frame, place extra counters beside it, and tell a partner the tens and ones.
Count 12 classroom pencils, put ten in a cup, and describe the pencils in the cup and the ones left out.

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