Banking · Saving & Interest · HTML Lesson

What Is Compound Interest?

An online lesson and video on the power of compound interest — how it differs from simple interest, how it accelerates savings growth over time, and how the same force intensifies debt when carrying a balance. The lesson and video are free. An accompanying worksheet is available with Full Membership.

Grades 9–12 HTML Lesson 45–60 min Free Lesson Worksheet: Full Membership

What is compound interest worksheet illustration

What Students Learn

Learning objectives

The difference between simple interest and compound interest — and why compound interest produces faster growth
How “interest on interest” causes savings to grow exponentially rather than at a flat rate
How to apply the compound interest formula to calculate the future value of a savings or investment
Why starting to save early makes a significant difference — and how time is the most powerful variable in compounding
How compound interest works in reverse — intensifying credit card debt and loan balances when payments fall short
The importance of compounding frequency (daily, monthly, annually) when comparing financial products

Video Lesson

Watch: What Is Compound Interest and How to Calculate It

For Teachers

How to use this lesson

Use this lesson as the follow-on to simple interest — students should already know how to calculate I = P × R × T before taking this step. Open with the video, then work through a side-by-side example: the same $1,000 over 20 years at 5%, using simple vs. compound interest. The gap at year 20 tends to be a memorable reveal.

Discussion: Where does compound interest work for you? (Savings accounts, investments, retirement accounts.) Where does it work against you? (Credit card balances, payday loans, student loans.) This dual framing helps students understand that the same math applies — it just depends on which side of the equation they are on.

Best positioned after simple interest and before credit card interest lessons. Strong connector between banking and credit units — compound interest is the mechanism that makes both savings and credit card debt behave the way they do.

Lesson Plan

Understanding compound interest — full lesson plan

Duration: about 70 minutes · Grades 7–12

Objective

By the end of the lesson, students will understand compound interest, differentiate it from simple interest, compute it using the formula, and grasp its long-term effects on savings and loans.

Materials needed

The “What Is Compound Interest?” video (above)
Calculators and student notebooks
Whiteboard and markers

Procedure

Introduction (10 minutes). Ask: “Would you rather have $100 today or $105 a year from now? What about in two years?” Connect their answers to the power of letting money grow, then play the video.

Discussion (15 minutes). Discuss:

How do you differentiate compound interest from simple interest?
What does “interest on interest” mean?
What are the long-term implications of compound interest on savings?
How does the frequency of compounding (daily vs. yearly) influence growth?
Why is it advised to start investing early?

Activities (25 minutes). Students use calculators to see how different amounts grow with compound interest over time, then build a side-by-side chart comparing compound vs. simple interest growth and discuss their observations.

Quiz (15 minutes). A quiz covering the concept, its difference from simple interest, its calculation, and its implications.

Conclusion (5 minutes). Recap why compound interest matters, highlighting its two-sided nature: beneficial in savings but costly with compounded debt.

Extension. Students research a financial product (a savings account, credit card, or loan) and write a brief report on how compound interest affects it.

The lesson content and video above are free to use. The printable worksheet below is available with Full Membership.

Printable Worksheet · Full Membership