Money Math · Lesson Plan

Estimating Differences with Money

Estimating gives a quick answer that is close to exact — handy at the store for checking your change or whether you have enough left to buy something else. This lesson teaches students to estimate a money subtraction by rounding each amount to the nearest whole dollar, then subtracting. Students practice on fifteen money difference problems.

Grades 3–6 Lesson Plan 30–45 minutes Free Lesson

Estimating differences with money lesson illustration

For Teachers

Lesson at a glance

Topic: Money Math
Grade Level: Grades 3–6
Resource Type: Lesson + Worksheet
Estimated Time: 30–45 minutes
Format: Lesson + worksheet + answer key
Materials: Printable lesson, worksheet, answer key, calculator

What Students Learn

Learning objectives

Explain what it means to estimate a difference
Round a money amount to the nearest whole dollar
Estimate a subtraction problem involving money
Explain why estimation is useful when shopping
Check whether an estimate is reasonable

Materials

What you’ll need

Printed copies of the lesson and worksheet (one per student)
Pencils
Whiteboard or projector for worked examples

Key Terms

Vocabulary

Estimate: An answer that is close to exact but does not require full computation.
Difference: The result of subtraction.
Rounding: Adjusting a number to the nearest whole dollar or place value.
Reasonable: An answer that makes sense for the problem.
Whole dollar: A money amount with no cents.
Subtraction: Taking one amount away from another.

For Teachers

Lesson plan

Estimated time: one 30–45 minute class period.

Lesson sequence

Introduction (5 min). Use the $18.95 − $2.97 example: why estimate instead of doing exact borrowing and regrouping?
Teach the method (10 min). Round each amount to the nearest whole dollar, subtract, and check that the answer is reasonable. Connect to checking change at the store.
Worksheet (15 min). Students estimate fifteen money difference problems.
Review (10 min). Check answers with the answer key and discuss when estimating is good enough.

Assessment

Assess the completed worksheet against the included answer key.

Discussion

Discussion questions

What does it mean to estimate a difference?
How do you round a money amount to the nearest dollar?
Why is estimating useful when you are shopping?
When would you need an exact answer instead of an estimate?
How can you tell if your estimate is reasonable?

Printable Lesson, Worksheet & Answer Key