ANSWER KEYS - Teacher Use Only

Adding & Subtracting Fractions | Grade 4

Student Concept Worksheet Answers
1
7/8
3/8 + 4/8 = 7/8 (add numerators: 3+4=7, keep denominator: 8)
2
4/10 = 2/5
7/10 - 3/10 = 4/10 (subtract numerators: 7-3=4). Simplify: 4/10 = 2/5 (divide by 2)
3
3 5/6
1 2/6 + 2 3/6: Add wholes (1+2=3), add fractions (2/6+3/6=5/6). Answer: 3 5/6
4
2/5 + 2/5 = 4/5
Jenna drank 4/5 of the bottle
Practice Worksheet Answers

Part A: Adding Fractions

#ProblemAnswerWork
12/5 + 1/53/52+1=3, keep 5
23/8 + 3/86/8 = 3/43+3=6, simplify 6/8=3/4
31/6 + 4/65/61+4=5, keep 6
45/12 + 3/128/12 = 2/35+3=8, simplify 8/12=2/3

Part B: Subtracting Fractions

#ProblemAnswerWork
55/6 - 2/63/6 = 1/25-2=3, simplify 3/6=1/2
67/8 - 3/84/8 = 1/27-3=4, simplify 4/8=1/2
79/10 - 4/105/10 = 1/29-4=5, simplify 5/10=1/2
86/8 - 2/84/8 = 1/26-2=4, simplify 4/8=1/2

Part C: Mixed Numbers

#ProblemAnswerWork
92 1/4 + 1 2/43 3/42+1=3, 1/4+2/4=3/4
103 2/5 + 2 2/55 4/53+2=5, 2/5+2/5=4/5
114 5/6 - 2 1/62 4/6 = 2 2/34-2=2, 5/6-1/6=4/6=2/3
125 3/8 - 1 1/84 2/8 = 4 1/45-1=4, 3/8-1/8=2/8=1/4

Part D: Word Problems

13
3/8 + 2/8 = 5/8
Maria used 5/8 of the roll of ribbon
14
7/10 - 3/10 = 4/10 = 2/5
Jake has 2/5 (or 4/10) of the pizza left
15
1 2/5 + 2 1/5 = 3 3/5
Sophie walked 3 3/5 miles in total

Challenge Questions:

#16: Carlos is NOT correct. The correct answer is 5/6, not 5/12. When adding fractions with like denominators, you only add the numerators. The denominator stays the same because it represents the size of the pieces.

#17: The missing number is 4. (4/8 + 3/8 = 7/8)

FAST Practice Quiz Answers
1
B) 7/8
3/8 + 4/8 = 7/8. Add numerators (3+4=7), keep denominator (8). NOT 7/16!
2
B) 1/2
9/10 - 4/10 = 5/10 = 1/2 (simplified by dividing by 5)
3
A) 2/6 + 3/6 = 5/6
The model shows 2 purple parts + 3 violet parts = 5 shaded parts out of 6 total
4
Select: First two options only
2/5 + 2/5 = 4/5 - Correct!
6/8 - 2/8 = 4/8 - Correct! (also equals 1/2)
1/4 + 1/4 = 2/8 - WRONG! Should be 2/4 (not 2/8)
5/6 - 3/6 = 1/3 - WRONG! Should be 2/6 = 1/3... Actually this IS correct when simplified! Accept if students selected this.
5
A) 3 7/8
2 3/8 + 1 4/8: Add wholes (2+1=3), add fractions (3/8+4/8=7/8). Answer: 3 7/8
6
C) 1/2
5/6 - 2/6 = 3/6 = 1/2 (simplified). B) 3/6 is also correct but not simplified. C is the better answer.
FAST Quiz Scoring Guide
Score Interpretation Recommended Action
6/6 Mastery Ready for IXL practice. Consider extension to unlike denominators (Grade 5 preview).
4-5/6 Approaching Mastery Review simplifying answers. Practice mixed number operations.
2-3/6 Developing Reteach with fraction bar visuals. Focus on "add numerators, keep denominator" rule.
0-1/6 Needs Intervention Small group instruction with physical fraction tiles. Address the "adding denominators" misconception directly.
FAST Success Kit | Grade 4 | FL B.E.S.T. Standards: MA.4.FR.2.1, MA.4.FR.2.2 | Answer Key - Teacher Use Only