CCSS.Math.Content.5.NBT.A.3
The standard
Read, write, and compare decimals to thousandths.
Common Core State Standards for Mathematics · Number and Operations in Base Ten
What this standard means
Students need to read decimals, write them in standard form, word form, and expanded form, and compare decimals through the thousandths place. They should understand that digits have different values based on place, including tenths, hundredths, and thousandths.
Mastery looks like correctly naming 0.407 as four hundred seven thousandths, writing it as 4 tenths plus 7 thousandths, and choosing the greater decimal with a clear reason. Students often confuse hundredths and thousandths, ignore zeros, or compare decimals like whole numbers.
Ways to teach it
- Hands-on activity: Give students base-ten blocks or decimal grids to build 0.3, 0.30, and 0.300, then explain why they match.
- Discussion prompt: Ask, “Which is greater, 0.62 or 0.607, and how do you know without guessing?”
- Quick assessment: Have students write 0.805 in word form, expanded form, and place it correctly on a number line.
- Real-world connection: Use three race times, such as 12.4, 12.37, and 12.406 seconds, and rank them from fastest to slowest.
Plan a lesson for CCSS.Math.Content.5.NBT.A.3
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Related standards
- CCSS.Math.Content.5.NBT.A.3b
Compare two decimals to thousandths based on meanings of the digits in each place, using >, =, and < symbols to record the results of comparisons.
- CCSS.Math.Content.4.NF.C.7
Compare two decimals to hundredths by reasoning about their size. Recognize that comparisons are valid only when the two decimals refer to the same whole. Recor...
- CCSS.Math.Content.2.NBT.A.3
Read and write numbers to 1000 using base-ten numerals, number names, and expanded form.
- CCSS.Math.Content.5.NBT.A.3a
Read and write decimals to thousandths using base-ten numerals, number names, and expanded form, e.g., 347.392 = 3 × 100 + 4 × 10 + 7 × 1 + 3 × (1/10) + 9 × (1/...