Patterns and Input/Output Tables — Answer Key
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
The pattern 2, 4, 8, 16 follows the rule add 2.
Corrected: The pattern 2, 4, 8, 16 follows the rule multiply by 2.
Each term doubles, so the Grade 4 rule is multiply by 2; adding 2 would give 2, 4, 6, 8.
2. Fix the sentence:
The next term in 1, 3, 9, 27 is 54.
Corrected: The next term in 1, 3, 9, 27 is 81.
The rule is multiply by 3, so 27 times 3 equals 81 in this Grade 4 sequence.
3. Fix the sentence:
In 100, 90, 80, 70 the rule is subtract 5.
Corrected: In 100, 90, 80, 70 the rule is subtract 10.
Each Grade 4 term decreases by 10, so the rule is subtract 10, not subtract 5.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. The pattern 3, 9, 27, 81 follows the rule multiply by 3.
Each Grade 4 term is 3 times the previous, so the rule is multiply by 3.
2. The next term after 5, 10, 20, 40 is 80.
Doubling 40 gives 80, continuing this Grade 4 multiplication pattern.
3. In 64, 56, 48, 40 the rule is subtract 8.
Each Grade 4 term decreases by 8, so the rule is subtract 8.
4. Continuing 2, 6, 18, 54, the missing term is 54.
The rule is multiply by 3, and 18 times 3 equals 54 in this Grade 4 pattern.
Part C: Short Answer
Answer each question in one or two complete sentences.
1. Describe the rule for 4, 8, 16, 32 and give the next two terms in this Grade 4 pattern.
Sample answer: The rule is multiply by 2. Each term doubles the previous one, so after 32 comes 64, and after 64 comes 128 because 64 times 2 equals 128.
Spotting doubling patterns helps Grade 4 students see multiplicative rules required in CCSS 4.OA.5.
2. Explain the difference between an addition rule and a multiplication rule using Grade 4 examples.
Sample answer: An addition rule changes by the same amount, like 5, 10, 15, 20 (add 5). A multiplication rule multiplies by the same factor, like 5, 10, 20, 40 (multiply by 2), so the gap grows.
Distinguishing rule types is essential for Grade 4 pattern reasoning under CCSS 4.OA.5.