What is an ETF?
An ETF is a basket. Instead of buying one company, one purchase can give you tiny pieces of hundreds of companies.
ETF = exchange-traded fundMission 01 · Learn how money grows
Your money can grow while you sleep.
Small amounts invested in a broad S&P 500 ETF can add up over decades. The secret isn't magic—it's time.
See $100 grow45 years to grow$54K contributed
Mission progressLong-term wealth mission
LEVEL65
🌱$100each month
📅20 → 6545 years
📈10%hypothetical
🌳≈ $1.05Mmodeled balance
Rule of 72 · 72 ÷ 10 ≈ 7.2 years per doubling6 gold points = about 6 completed doubling periods in 45 years*
🛡️ Returns aren't guaranteed.
Money, translated
Three big ideas—and one useful shortcut.
You don't need to be a finance genius. Start with these.
What is the S&P 500?
It's an index that tracks about 500 large U.S. companies. Funds such as VOO are designed to follow it.
One fund · many businessesWhat is compounding?
Your investment may earn returns. Later, those returns may earn returns too—like a snowball that keeps collecting snow.
Growth building on growth72÷10%=≈ 7.2 years
04 · QUICK SHORTCUT
The Rule of 72
Want a quick estimate of how long money could take to double? Divide 72 by the hypothetical annual return. At 10%, that's about 7.2 years. Over 45 years, that works out to about six full doubling periods.
*The Rule of 72 is an estimate for one amount growing at a steady rate. Our $100-a-month example is different because you keep adding new money, and real market returns are never steady or guaranteed.Growth simulator
Plot your own mission.
Change the controls and watch the model respond. Try 7% as a more cautious example, then compare it with 10%.
Important: This calculator uses a steady hypothetical return. Real markets rise and fall, fees and taxes matter, and no return is promised.
Modeled balance at age 65$1,048,250
You add $54,000 Modeled growth $994,250
Your launch sequence
Learn first. Then invest with an adult.
Build your safety fund
Money you may need soon belongs in a safe, accessible place—not the stock market.
Choose an account
Adults can explore a brokerage or retirement account. A young person usually needs a parent or guardian to open a custodial account.
Research the fund
Look at what the ETF owns, its fee, how closely it follows its index, and the risks in its official materials.
Automate and be patient
Regular contributions and a long timeline matter more than trying to guess the market's next move.
For families & classrooms
Turn $100 into a conversation.
Ask a young person to predict the result, move the return slider, and compare starting at 20 versus 30. The lesson is not “you'll get rich.” It's that time, consistency, diversification, and risk all matter.
Try this questionWhat changes more: adding $25 a month, or starting ten years earlier?Test it in the simulator →