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.

Today’s money mission

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.

What you need to know

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.

Real-life example

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

Progress Penguin connection

Open your savings balance and check whether interest earned is added back to the balance or listed as a separate line. If it is added to the balance, your interest will earn further interest next cycle. That is compounding — the mechanism this lesson describes.

Activity preview

Choose the best money move

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

Create or review a savings goal

Open your kid dashboard and create or review one savings goal with a clear name, amount, and date.

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