CCSS.Math.Content.3.NBT.A.1
The standard
Use place value understanding to round whole numbers to the nearest 10 or 100.
Common Core State Standards for Mathematics · Number and Operations in Base Ten
What this standard means
Students need to round whole numbers to the nearest ten and nearest hundred. They should use place value, not just memorize a rhyme. They need to identify the target place, check the digit to the right, and choose the closest ten or hundred.
Mastery looks like students explaining why 346 rounds to 350 and 300, using a number line or place value language. Common trouble spots are numbers with 5 in the deciding place, numbers near a hundred, and mixing up which digit to look at when rounding to tens versus hundreds.
Ways to teach it
- Hands-on activity: Give students base-ten blocks and number cards, then have them build each number and round it to the nearest ten and hundred.
- Discussion prompt: Ask, “Is 250 closer to 200 or 300, and how do you know?” then have partners defend their answer.
- Quick assessment: Show 467, 735, and 820, and have students round each to the nearest ten and hundred on sticky notes.
- Real-world connection: Use store prices like $183 and $247, and ask students to estimate totals by rounding to the nearest hundred.
Plan a lesson for CCSS.Math.Content.3.NBT.A.1
Generate a complete lesson plan aligned to this standard, with objectives, activities, and materials. Free, no account needed.
Related standards
- CCSS.Math.Content.1.NBT.B
Understand place value.
- CCSS.Math.Content.5.NBT.A.4
Use place value understanding to round decimals to any place.
- CCSS.Math.Content.4.NBT.A.3
Use place value understanding to round multi-digit whole numbers to any place.
- CCSS.Math.Content.4.NBT.A
Generalize place value understanding for multi-digit whole numbers.