Lesson 3 · Written for kid, teen, and little
Compound interest
Drag the sliders to see how time builds wealth.
Here's how compounding works: when your money earns a return and you keep that return invested, it can earn more too. With a positive return over many years, it can grow like a snowball. Starting earlier gives compounding more time to work, but investments can lose value and growth is not guaranteed. ❄️
Words to know
2Compound interest
When your money earns money, and then your earnings start earning too — growth that snowballs over time.
Annual return
The percentage gain or loss on an investment over one year. A positive return increases value; a negative return reduces it.
Drag the sliders to see compound interest in action. Try investing $30 for 30 years — see the snowball.
Future value
$6,197
at 10% a year
Contributions
$3,600
Compounding turns 1.7× your contributions into this value.
Real markets rise and fall — this assumes the same return every year, before inflation. It is an estimate, not a promise.
Monthly contribution
$30
Years
10 yrs
Increase Years beyond its starting setting until the projected value is at least 1.5 times your contributions.
In the full lesson
- 1Play with the numbers
Vine has 107 lessons like this one, each written three ways so a 7-year-old and a 17-year-old both get a version that fits.
The practice portfolio is open.
Start practicingMore in Start here
- 🏢What is a stock?How owning a share means owning the business.
- ⏳Time in market beats timing itA long-term plan means fewer guesses about when to jump in or out.
- 🛒Needs vs. WantsNeeds keep you okay; wants make life fun — and knowing which is which protects your money.
- 🥧Making a BudgetA budget is a plan you make for your money before you spend it.
- ⚖️The Hidden Cost of ChoosingEvery yes to one thing is a quiet no to something else.
- ⚖️Why Prices Go Up and DownPrice is a tug-of-war between how much exists and how many people want it.