Maryland Math 1.NOS.B.3.a

Math1st GradeNumber and Operation Sense

The Standard

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.

Compose and decompose two-digit numbers into tens and ones using objects or drawings, and equations (e.g., 10 + 4 = 14; 38 = 30 + 8).

Maryland College and Career Ready Standards for Mathematics (2025) · UNDERSTAND PLACE VALUE AND REPRESENTATIONS OF NUMBERS.

Teacher's field guide

What Students Need to Do: Students group objects by tens, with any extras left as ones. They draw the groups, name the number, and write an addition equation for its parts.
What Mastery Looks Like: Given 46, a student draws four groups of ten and six singles, then writes 46 = 40 + 6. Given the drawing, they can name 46 without counting every item.
Common Misconceptions: Some students write 38 as 3 + 8 instead of 30 + 8. Others count a group of ten as one object when finding the total.
How to Assess It: Exit ticket: Draw 36 using groups of ten and single dots. Write an equation that shows the value of each part.

Lesson moves

Give pairs 53 straws and rubber bands; have them bundle tens, leave singles, and write an equation for 53.
Ask: Mia says 52 = 5 + 2. Draw a picture and write a sentence explaining her mistake.
Play Build It: draw a two-digit number card, sketch tens sticks and ones dots, then write the matching equation.
Set a pretend price of 47 cents; use dimes and pennies to make it, then write 40 + 7 = 47.

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