Grade 4 (age 9-10)

grade 4 Understanding Decimals

Decimals such as 0.1 and 0.5 are used for amounts smaller than 1. Split 1 into 10 equal parts and one part is 0.1; three of them make 0.3, and ten of them make 1. 0.3 is the same amount as the fraction 3/10, and a decimal bigger than 1, like 1.5, is the 1 to the left of the decimal point plus the 0.5 to the right. Change the number to see its place on the number line and how many of the 10 parts of the bar are shaded.

What Is a Decimal?

🔍 Writing Amounts Smaller Than 1

①Half a pizza is 0.5 of a pizza

②Someone 1 m 20 cm tall is 1.2 m tall

③The dot in a decimal is called the decimal point

④The digit right after the decimal point counts tenths: how many of the 10 equal parts

Decimals on a Number Line

Decimal0.3

💡 Counting Tenths

①0.1 is one of 10 equal parts of 1

②Three tenths make 0.3, and ten tenths make 1

③1.5 is 1 plus 0.5, which is fifteen tenths

④To compare decimals, compare the whole-number parts first; if they are equal, compare the tenths

Fractions and Decimals

🔗 Fractions and Decimals

①1/10 = 0.1

②5/10 = 0.5, which is the same as 1/2

③A fraction with denominator 10 becomes a decimal when you write its numerator in the tenths place

④On the bar, the number of shaded parts is the numerator and 10 is the denominator

Summary

What a Decimal Means

0.1 = 1/10

One of 10 equal parts of 1

Fraction to Decimal

310 = 0.3

Write the numerator of a fraction over 10 in the tenths place

Decimals Bigger Than 1

1.5 = 1 + 0.5

Left of the decimal point is the whole number; right of it is the part smaller than 1

🎯 Summary

①One of 10 equal parts of 1 is 0.1

②Ten 0.1s make 1

③A fraction with denominator 10 can be written as a decimal with one decimal place

④Compare decimals by the whole-number part first, then the tenths

⑤A decimal bigger than 1, like 1.5, can be read as 1 and 0.5

Examples and Unit Test

Example 1

Write 7/10 as a decimal.

For a fraction with denominator 10, write the numerator in the tenths place.

The numerator is 7, so it is 0.7.

▸ 0.7

Shading 7 of the 10 parts of the bar shows 0.7.

Example 2

What do ten 0.1s make?

0.1 is one of the 10 parts of the bar.

Ten 0.1s fill all 10 parts, so they make 1.

▸ 1

That is why 1.0 and 1 are the same number.

Unit Test

Which fraction is equal to 0.3?

①3100

②310

③103

④13

▸ ② 310

The tenths digit tells how many of the 10 parts there are.

0.3 is 3 of the 10 parts, so it is 3/10.

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Fraction Addition & Subtraction

Order of Operations

Last updated 2026-10-17