Back to Compound Interest Intro
11+interest-growth

Interest on interest

Explore why the snowball analogy captures compound interest perfectly: the bigger it gets, the faster it grows.

In this lesson

Interest on interest is part of Compound Interest Intro. This preview shows how interest-growth connects to everyday family decisions such as earning, saving, spending choices, goals, approvals, or parent-guided money conversations inside Progress Penguin.

Think about this money choice

Imagine this situation: Year 1: 10000 in local currency earns 10% = 1000 in local currency interest, new balance 11000 in local currency. Year 2: interest is calculated on 11000 in local currency.

How it works

The snowball analogy captures compound interest perfectly: the bigger it gets, the faster it grows. The same percentage applied to a larger base produces an increasingly larger absolute amount each period.

Apply it to a real decision

Real-life money moment: 10000 in local currency compounded at 10% annually. Fill in: Year 1 balance =? Year 3 balance =?

Activity preview

Choose the best money move

Use what you just learned. Choose the option you can explain.

Build your own savings goal

Progress Penguin will guide you through the goal name, target amount, and deadline. When you finish, you will return to this exact lesson step.

Quiz preview

After many years, compound vs simple becomes:

Slightly smaller
Identical
Negative
Dramatically larger

Year 1: 10000 in local currency earns 10% = 1000 in local currency interest, new balance 11000 in local currency. Year 2: interest is calculated on 11000 in local currency. How much interest in Year 2?

1100 in local currency — 10% of the new 11000 in local currency balance
1000 in local currency — same as Year 1
900 in local currency — the rate decreases
2000 in local currency — compounding doubles it