CCSS.Math.Content.5.NBT.A.3a
The standard
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 × (1/100) + 2 × (1/1000).
Common Core State Standards for Mathematics
What this standard means
Students need to read and write decimals through thousandths in three forms: standard form, word form, and expanded form. They should know what each digit is worth, including tenths, hundredths, and thousandths, and connect the decimal point to place value.
Mastery looks like moving between forms without guessing. Students can explain that 4.206 means 4 ones, 2 tenths, 0 hundredths, and 6 thousandths. Common trouble spots are reading 0.045 as forty-five tenths, skipping zeroes in word form, and writing expanded form with digits instead of values.
Ways to teach it
- Have students build decimal numbers with place-value disks or grids, then record each number in standard, word, and expanded form.
- Ask students to explain why 0.304 is not the same as 0.34 using words, a model, and expanded form.
- Show 6.072 and have students write it in word form and expanded form on an exit ticket.
- Use grocery prices or race times to have students read decimals aloud and identify the value of each digit.
Plan a lesson for CCSS.Math.Content.5.NBT.A.3a
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Related standards
- 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.3
Read, write, and compare decimals to thousandths.
- CCSS.Math.Content.4.NF.C.6
Use decimal notation for fractions with denominators 10 or 100.
- CCSS.Math.Content.4.NBT.A.2
Read and write multi-digit whole numbers using base-ten numerals, number names, and expanded form. Compare two multi-digit numbers based on meanings of the digi...