The Money Rule I’m Teaching My Kids Before Age 10

Teaching Kids About Money Before Age 10 — Why It Matters

Teaching kids about money before age 10 is one of the best investments a parent can make — and I say that as someone who wishes someone had done it for me.

My 7-year-old asked me something last week that stopped me mid-sentence.

“Dad, if I spend my allowance, is it gone forever?”

I thought about it for a second. And then I told him the one money rule I’m building our whole family finance system around — the rule I wish I’d learned decades earlier.

“Yes. But if you invest it, it comes back — bigger.”

That’s it. That’s the whole lesson. But getting a child to actually understand what that means — and believe it — takes more than one sentence. Here’s how I’ve been doing it.

The One Money Rule for Teaching Kids About Money

Most adults were taught one money rule as kids: save your money.

Save it in a piggy bank. Save it in a savings account. Don’t spend it. Keep it safe.

That’s not a bad lesson. But it’s incomplete — and that gap cost me years of investment growth I’ll never get back.

The rule I’m teaching my kids is slightly different:

Spend some. Save some. But make the rest work for you.

Money that sits in a piggy bank stays the same. Money that’s invested grows — quietly, automatically, without them doing anything. That difference, compounded over 60+ years, is the difference between struggling and comfortable.

According to the Consumer Financial Protection Bureau, financial habits and attitudes begin forming as early as age 7 — which is exactly why starting these conversations before age 10 matters so much.

→ How does compounding actually work? What Is Compound Interest?

How I Explain This to a 7-Year-Old

I don’t use words like “compound interest” or “equity markets” with my oldest. I use three things he already understands: his piggy bank, LEGO, and time.

The LEGO analogy:

“You know how when you build a LEGO set, you start with a pile of bricks and end up with something bigger and cooler? Investing is like that — but your money is the bricks, and they keep adding more bricks by themselves while you sleep.”

He liked that one. It clicked.

The piggy bank upgrade:

“Your regular piggy bank holds your money. But your investment account is a piggy bank that makes more money on its own every year. The longer you leave it alone, the more it makes.”

He now refers to his investment account as his “smart piggy bank.” I’ll take it.

What My 3-Year-Old Understands (And It’s Enough)

My youngest is 3. He doesn’t understand investing. He doesn’t need to yet.

What he understands: coins go in the piggy bank. When it’s full, something good happens. And sometimes Dad puts money somewhere special that’s “for when you’re big.”

That’s enough. The habit of associating money with intention — rather than just spending — starts forming now, even if the understanding comes later.

His account already has $750 in it, 100% in QQQM. He has no idea. But when he’s 25 or 30 and that account has grown for two decades, he’ll understand why we started so early.

→ See both kids’ portfolios: I Opened a Stock Account for My 7-Year-Old

Why Teaching Kids About Money Early Changes Everything

I didn’t learn about investing until my late twenties. By then, I’d missed years of compounding that I’ll never recover.

Not because I didn’t have money to invest. Because nobody ever told me this was something I should be doing — or how.

I don’t want that for my kids. I want them to reach adulthood already understanding that money can work for them, not just the other way around. That investing isn’t something complicated that “finance people” do — it’s something a 7-year-old can do with an ETF and $50.

The earlier that idea becomes normal, the better. And teaching kids about money before age 10 — through real conversations, real accounts, and simple systems like the 3-bucket rule — is the most practical way I’ve found to do it.

The One Rule, Summarized

If I had to distill everything into one sentence for my kids — the one money rule I want them to carry into adulthood — it’s this:

Don’t just save your money. Put it somewhere it can grow while you’re busy living your life.

That’s compound interest. That’s index fund investing. That’s the whole idea — explained to a 7-year-old with a LEGO analogy and a “smart piggy bank.”

Simple. Early. Consistent. That’s the plan.

→ How I talk to my kids about money: How I Explain Money to My Kids (Ages 7 and 3)
→ Their actual investment accounts: I Opened a Stock Account for My 7-Year-Old
→ What is compound interest? Why Starting Early Changes Everything