Adding and subtracting money is a bridge skill: students use familiar dollars and coins while practicing place value, regrouping, estimation, and word-problem reasoning. Many Grade 3 students can count coins but still struggle when money is written as dollars and cents, especially when a problem requires regrouping across the decimal point.
The Common Core Grade 2 money standard asks students to solve word problems with bills and coins using dollar and cent symbols. By Grade 3, a strong lesson should connect that earlier coin knowledge to written addition and subtraction, then move quickly into real-world problems. This guide gives teachers, parents, and tutors a concrete teaching sequence, examples, mistakes to watch for, and a five-question exit ticket.
Before the Lesson: Check Three Prerequisites
Do not start with vertical algorithms until students can explain the money values they are using. A quick warm-up should confirm that students can:
- Name the value of a penny, nickel, dime, quarter, one-dollar bill, and five-dollar bill.
- Explain that 100 cents equals 1 dollar.
- Read $3.47 as 3 dollars and 47 cents.
- Add and subtract two- and three-digit whole numbers with regrouping.
If students miss more than one of those, begin with physical coins or a coin-value chart before moving to decimal notation.
Lesson Sequence: Concrete, Visual, Algorithm
Step 1: Build the Amounts
Give students two amounts such as 75 cents and 48 cents. Ask them to build each amount with coins, combine the coins, and count the total. The key moment is the regrouping: 75 cents + 48 cents = 123 cents, and 123 cents is $1.23.
Step 2: Use a Dollars-Tens-Ones Table
Before writing the standard algorithm, use a place-value table. This helps students see that dimes are the tenths place and pennies are the hundredths place.
| Amount | Dollars | Dimes | Pennies |
|---|---|---|---|
| $2.68 | 2 | 6 | 8 |
| $1.47 | 1 | 4 | 7 |
| Total before regrouping | 3 | 10 | 15 |
| Total after regrouping | 4 | 1 | 5 |
The total is $4.15. The table makes it clear why 15 pennies become 1 dime and 5 pennies, and why 10 dimes become 1 dollar.
Step 3: Move to Vertical Addition and Subtraction
Once students understand the regrouping, write the same problem vertically and require one non-negotiable habit: line up the decimal points.
$2.68 + $1.47 ------- $4.15
For subtraction, start with making change because the context makes the regrouping meaningful.
$5.00 - $3.78 ------- $1.22
Check the answer by adding back: $3.78 + $1.22 = $5.00.
Worked Examples to Model Out Loud
Example 1: Total Cost
Problem: A notebook costs $2.35 and a pencil costs $0.80. What is the total cost?
Setup: Line up the decimal points.
$2.35 + $0.80 ------- $3.15
Answer: The total cost is $3.15.
Example 2: Change from Five Dollars
Problem: A snack costs $2.64. How much change do you get from $5.00?
$5.00 - $2.64 ------- $2.36
Answer: The change is $2.36.
Example 3: Two-Step Money Problem
Problem: Jada has $8.25. She buys a marker for $1.75 and a folder for $2.40. How much money does she have left?
Step 1: Add the costs: $1.75 + $2.40 = $4.15.
Step 2: Subtract from the starting amount: $8.25 – $4.15 = $4.10.
Answer: Jada has $4.10 left.
Common Mistakes and Quick Fixes
- Decimal points are not lined up. Use graph paper or a place-value chart until alignment is automatic.
- Students subtract the smaller digit from the larger digit in each column. Ask them to say the full amount aloud before computing: “I have five dollars and zero cents. I am spending two dollars and sixty-four cents.”
- Students forget the dollar sign or cents label. Require a label in every final answer.
- Students choose the wrong operation in word problems. Have them mark whether the problem asks for a total, a difference, change, or how much more is needed.
- Students trust an unreasonable answer. Estimate first. If a snack costs about $3 and you pay $5, the change should be about $2.
Mini Practice Set
- $1.45 + $2.30 = ____
- $4.75 + $0.68 = ____
- $7.00 – $2.58 = ____
- A book costs $3.25 and a bookmark costs $0.95. What is the total cost?
- Leo has $10.00. He spends $4.36. How much does he have left?
Answer Key
- $3.75
- $5.43
- $4.42
- $4.20
- $5.64
Five-Minute Exit Ticket
Use this at the end of the lesson. Students should complete it without coin manipulatives unless they still need support.
- Write 3 dollars and 8 cents using a dollar sign.
- Find $2.75 + $1.48.
- Find $6.00 – $4.29.
- A student buys two items: $1.35 and $2.15. Does $4.00 cover the cost? Explain.
- Estimate first, then solve: $9.50 – $3.87.
A student is ready to move forward when they line up decimal points correctly, explain regrouping in dollars and cents, and choose the correct operation in a short word problem.
More Grade 3 Practice
ViewMath Grade 3 resources include money, place value, operations, fractions, geometry, and word-problem practice with answer keys. Use the recommended Grade 3 books in the sidebar when students need more mixed review after this focused lesson.
