Roots of Reason
Roots of Reason
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name the whole first
Anchor Chart · Grade 5 · 5.NF.B.6

Fraction Word Problems

Name the whole each fraction counts, draw it, then check the size of the answer.
1Multiply, or Something Else?
2/5 of the class are girls. 1/8 of the girls wear glasses. What fraction of the class?
✓ multiply. 1/8 of 2/5 is 1/20
2/5 of a pizza is left. Jamie eats 1/8 of the whole pizza. How much is left?
✗ subtract. 2/5 - 1/8 is 11/40
Same numbers, different questions. Multiply when one fraction counts a part of the other.
2Name the Whole, Draw It
A recipe uses 2/3 cup of oats. You make 3/4 of the recipe.
1 cup, the whole2/3 cup of oats3/4 of the 2/3 cup is 1/2 cup
The 3/4 counts the oats, not the cup. Cut the 2/3 into four parts and keep three.
3Every Part Times Every Part
21/211/321/22/31/6
2 + 12 + 23 + 16 = 3 13
✗ 2 16
wholes times wholes
✓ 3 13
all four pieces counted
Wholes times wholes, fractions times fractions, drops the two shaded pieces.
4Check the Size First
what you started with× 3/4smaller× 4/4the same× 1 1/3bigger
Decide whether the answer should grow or shrink before you compute, then check that it did.