Sum Builders Worksheet Bundle
Session 1 NC.3.NBT.2 • Addition Workshop
Sum Builders: Place Value & Expanded Form
Name:
Date:
Math Toolkit: Place Value: The value of a digit based on its position (hundreds, tens, ones). Partial Sums: Adding each place value separately before finding the total sum.
Guided Model: Expanded Form Strategy No Regrouping Needed
Decompose Addends
342 = 300 + 40 + 2
+ 235 = 200 + 30 + 5
Add by Place Value
Hundreds: 300 + 200 = 500
Tens: 40 + 30 = 70
Ones: 2 + 5 = 7
Combine Partial Sums
500 + 70 + 7
= 577
Part 1: Place-Value Chart Breakdown
1. Find: 426 + 351 Estimate: ~780
| Hundreds (100s) | Tens (10s) | Ones (1s) |
|---|
| 400 | 20 | 6 |
| + 300 | + 50 | + 1 |
| | |
Final Sum:
2. Find: 514 + 273 Estimate: ~790
| Hundreds (100s) | Tens (10s) | Ones (1s) |
|---|
| 500 | 10 | 4 |
| + 200 | + 70 | + 3 |
| | |
Final Sum:
Part 2: Independent Partial-Sums Practice
3. Solve 637 + 251 using expanded form:
Expand:
Add 100s:
Add 10s:
Add 1s:
Total:
4. Solve 182 + 705 using expanded form:
Expand:
Add 100s:
Add 10s:
Add 1s:
Total:
Reasonableness Check: For Problem 3, round both addends to the nearest hundred:
600 + 300 =
(Is 888 close to 900? Yes/No)
Session 2 NC.3.NBT.2 • Visual Regrouping
Regrouping Ones & Tens: Visual Models
Name:
Date:
10 ones
Regroup to 1 Ten
When ones total 10 or more, trade 10 ones for 1 ten rod.
10 tens
Regroup to 1 Hundred
When tens total 10 or more (e.g., 14 tens = 140), trade for 1 hundred flat.
Model 1: Open Number Line Strategy Problem: 268 + 154
Start at the larger addend (268). Make place-value jumps: +100, then +50, then +4.
Start
268
+100
368
+30 (to 398)
398
+20
418
+4
422
Your Turn: Solve 375 + 248 on the open number line:
375
(+100s)
(+10s)
Sum = ?
Write your final sum:
Part 2: Regrouping Detector & Solution
A. 486 + 237 Check Regrouping
Will ones regroup? (6 + 7 = 13): Yes (1 ten 3 ones)
Will tens regroup? (80 + 30 + 10 = 120): Yes (1 hundred 2 tens)
Sum:
B. 562 + 195 Check Regrouping
Will ones regroup? (2 + 5): [ Yes / No ]
Will tens regroup? (60 + 90 = 150): [ Yes / No ]
Sum:
Mathematical Explanation Frame:
"When adding 486 + 237, I regrouped 13 ones into ten and ones. Then I regrouped 12 tens into hundred and tens."
Session 3 NC.3.NBT.2 • The Algorithm
The Standard Algorithm & Error Analysis
Name:
Date:
Connecting Strategies: 387 + 245 Sum = 632
Strategy A: Partial Sums
387
+ 245
500 (300 + 200)
120 (80 + 40)
+ 12 (7 + 5)
632
Strategy B: Standard Algorithm
1 1 -
3 8 7
+ 2 4 5
6 3 2
Record regrouped 10s and 100s at the top!
Part 1: Grid-Aligned Addition Practice
- Est: ~800
4 5 8
+ 3 6 4
- Est: ~750
5 7 9
+ 1 8 6
- Est: ~900
6 4 7
+ 2 8 5
Part 2: Math Detective • Critique the Reasoning
Leo solved the problem below, but his answer is incorrect. Look at his work, find his error, and correct it.
Leo's Work
Did he add the regrouped ten?
1
4 7 8
+ 2 5 6
6 2 4
Correct Work
Explain Leo's mistake:
Algorithm Rule: Always add ones first, then tens, then hundreds. If a place value sums to 10 or more, regroup immediately!
Session 4 NC.3.NBT.2 • Problem Solving
Word Problem Workshop & Challenge
Name:
Date:
Read-Plan-Solve-Check:
1. Read: Circle numbers & underline goal 2. Plan: Estimate sum 3. Solve: Show place value work 4. Check: Use inverse subtraction
Problem 1: School Book Drive Core Strategy
Oakridge Elementary collected 378 books in October and 456 books in November. How many total books did the school collect during those two months?
Step 1: Estimate
Round to nearest 100:
Est. Total: ~800 books
Step 2: Solve (Show Work)
Use any 3-digit strategy
Sentence Frame Answer:
"The school collected a total of books."
Check with Subtraction (Relationship):
- 456 =
Differentiated Challenge Level
Level A • Step-by-Step Regroup Ones Only
A farm stand sold 348 green apples and 225 red apples. How many apples were sold altogether?
Total apples:
Level B • 2-Step Challenge Total & Comparison
Carlos has 285 points. Maya has 139 more points than Carlos. How many points do they have in all?
Combined points:
Student Self-Check:
I decomposed by place value I regrouped 10s and 100s My answer is reasonable
