Credit · Credit Cards · HTML Lesson
The Compound Interest Trap
An online lesson and video on how compound interest works against credit card holders — why minimum payments barely dent a balance, how debt grows month over month, and what it takes to actually pay off a credit card. The lesson and video are free. An accompanying worksheet is available with Full Membership.
What Students Learn
Learning objectives
- How compound interest accumulates on a credit card balance — and why it is called a “trap”
- What happens when you only make the minimum payment — how long it takes to pay off a balance and how much total interest accrues
- How the APR translates into a monthly rate that compounds on the outstanding balance each billing cycle
- Why carrying a balance month to month is fundamentally more expensive than paying in full each cycle
- The true cost of a credit card purchase — comparing the sticker price to the total paid after months or years of interest
- How to break the minimum payment cycle and develop a concrete strategy for paying down credit card debt
Video Lesson
Watch: The Compound Interest Trap
For Teachers
How to use this lesson
Play the video, then work through a minimum payment example as a class: take a $1,000 balance at 20% APR with a $25 minimum payment and calculate how long it takes to pay off. The result — often years and hundreds of dollars in interest — tends to land hard with students who hadn’t considered how minimum payments work.
Discussion: Why do credit card companies set minimum payments so low? What happens if you only pay the minimum every month? If you increased your payment by $25 or $50 a month, how much faster would the balance disappear? These questions build students’ intuition for the math before they apply it on their own.
Best positioned after APR and compound interest basics — students should already understand what interest is before seeing how it compounds against them on a credit card. Strong closer for a credit card unit before moving to strategies for building credit responsibly.
Lesson Plan
The compound-interest trap — full lesson plan
Objective
Students will understand how compound interest works and recognize its impact on both debt and investments.
Key concepts
Compound interest has a dual nature. For an investor, earning interest on reinvested earnings drives exponential growth. Applied to debt — like a credit card balance — the same principle works against you, and debt can escalate quickly.
Understanding APY (Annual Percentage Yield) and the compounding frequency is essential. With daily or monthly compounding, balances grow faster, especially when only minimum payments are made. Because credit card issuers typically compound at higher daily rates, the burden intensifies. The best defense is to repay high-interest debt promptly and to weigh interest rates and compounding frequency carefully when evaluating any loan.
Suggested procedure
- Introduction. Open with a short scenario about how compound interest grew a real credit card or loan balance.
- Video. Play “Compound Interest Trap of Credit Cards and Loans”; students note key concepts.
- Discussion. Why do card companies compound daily? How does compounding frequency change the total owed? How can borrowers fight back?
- Activity. In small groups, calculate the total owed on a hypothetical debt over time, then discuss the value of paying more than the minimum.
- Worksheet & wrap-up. Students complete the worksheet; emphasize paying down high-interest debt.
Materials needed
- The “Compound Interest Trap of Credit Cards and Loans” video (above)
- The printable worksheet (below)
- Whiteboard or projector; a compound-interest calculator
The lesson content and video above are free to use. The printable worksheet below is available with Full Membership.
Printable Worksheet · Full Membership
Compound Interest & Credit Cards — Worksheet & Answer Key
A printable worksheet on compound interest and the credit card debt trap — APY, compounding frequency, and paying down high-interest debt — with an answer key for teacher use.
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