Maryland Math 3.NOS.A.1.a

Math3rd GradeNumber and Operation Sense

The Standard

3.NOS.A.1: Apply and extend place value understanding to whole numbers within 10,000.

Read and write whole numbers using base-ten numerals, number names, and expanded form.

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

Teacher's field guide

What Students Need to Do: Students read whole numbers and write them in digits, words, and expanded form. They move between these forms without changing the number.
What Mastery Looks Like: Given 406, a student writes “four hundred six” and 400 + 6. Given “three hundred seventy,” they write 370 and 300 + 70.
Common Misconceptions: Students may write 406 as 46 because they leave out the zero. They may write 400 + 60 for 406 or read 370 as “three hundred seven.”
How to Assess It: Exit ticket: Write 508 in words and expanded form. Then write the numeral for 600 + 40 + 2.

Lesson moves

Build 406 with base-ten blocks, then match the model to cards showing 406, “four hundred six,” and 400 + 6.
Ask, “Why does 406 need a zero?” Have students draw a place-value chart and explain their answer in two sentences.
Give pairs numeral, word, and expanded-form cards for 205, 370, and 614; have them match each set and check with a place-value chart.
Put a sign reading “205 books” on a classroom shelf; have students write the count in words and expanded form on a second sign.

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