TOPIC 6 · GRADES 3–4 FOUNDATION
Build and Decompose Fractions
Compose fractions from unit pieces and split them into useful sums.
MA.3.FR.1.2 · MA.4.FR.2.1BIG IDEA
A fraction can be decomposed in many valid ways. For example, 5/6 is five copies of 1/6 and also 2/6 + 3/6.
LEARN IT WITH A STORY
Build 5/6 from clay pieces
A clay bar divided into sixths can be arranged in different groups. Five sixths is five copies of 1/6, but it is also 2/6 + 3/6.
- 1Identify the unit piece: each clay block is 1/6.
- 2Count all selected unit pieces to make 5/6.
- 3Place the pieces into two or more groups; their numerators must still total 5.
Draw and explain
Find three different ways to decompose 7/8 into two fraction addends.
FRACTION WORD BANK
Tap a word, then turn the card
Say the word aloud before revealing its meaning. Tap again to return to the word.
WATCH AND NOTICE
Decompose Fractions into a Sum — 4th Grade
Pause when a model appears. Name the whole, denominator, numerator, and fraction before the teacher explains it.
Open on YouTube ↗WHAT TO KNOW
- Unit fractions are building blocks for every fraction.
- The pieces in a decomposition must total the original amount.
- Decomposing helps with later addition, subtraction, and mixed numbers.
WATCH OUT
There is usually more than one correct decomposition.
TRY IT
Move the split point to create different addition equations for the same bar.