“Don’t Stay In School.” That’s the title of a rap song on YouTube. More than 11 million people have viewed it. It was created by David Brown, a young twenty-something rapper with long, dyed red hair. He walks along a path in the trees and rants about the education system. Despite the provocative title, however, he isn’t against school.

When I first saw the video, I shared it on Facebook. I’m not the sort of guy who posts pictures of his food. But if I decided to post a hamburger, about a dozen of my friends would politely click “like.” So what do you think happened when I posted “Don’t Stay In School”? In a popularity contest among my friends, a burger would have crushed it.

You see, I’m a schoolteacher. Most of my friends are teachers. The title, “Don’t Stay In School,” was a fly in a glass of wine. But those who watched the video saw the wisdom of its message.

The young rapper’s beef is with the absence of real-world learning. Higher-level mathematics, for example, is mandatory in most schools. Everybody also learns some Shakespeare. But learning about laws, human rights, voting procedures, mortgages, how to get a job, and how to invest aren’t mandatory.

I think most schools let us down. I first started to learn about money from a wealthy mentor. From there, I read more than 400 personal finance books before I turned 35. I boiled my learning down to nine rules of wealth that I should have learned in school. By applying them, I became a debt-free millionaire in my late 30s.

No, I didn’t inherit money, nor did I take big risks.

I became a high school personal finance teacher. I worked at a school that viewed the subject as important.

Kids want to know about money. So do their parents. But most people run straight into adulthood with no more knowledge about building wealth than the typical eighth grader. Money is taboo.

Yes, I can hear your Aunt Matilda. “Talking about money really isn’t polite.” But that kind of thinking leads to huge personal debts, financial exploitation, and leveraged lifestyles on the edge. These problems are a lot like toenail fungus. They’re tough to clear up. Mr. and Mrs. Jones didn’t sign up for this.

But the Jones’s spend most (or all) of their income. They don’t know how to invest. They hire the wrong kinds of financial planners who usually rob them blind. They’re at the whim of big mortgages, credit card companies, and a consumption-based treadmill. They make such huge mistakes because, in school, nobody taught them otherwise. That’s why I wrote Millionaire Teacher: The Nine Rules of Wealth You Should Have Learned in School. Such rules are timeless.

So why did I write a second edition?

I wanted to update my examples. The investment landscape is also changing for the better. In the past, virtually every financial adviser stuffed their clients’ portfolios with actively managed mutual funds. Such products layer the pockets of advisers and their firms. But they’re bad for investors. Fortunately, people have demanded something better.

Enter the firms that many call Robo Advisers. Such firms have said, “Hey, people won’t be conned forever. Let’s offer something better.” These firms follow the rules I outline in this book. They’re companies worth knowing. Unlike most banks and investment firms, they don’t play their clients for fools.

Other great investment products have also come on the market for DIY investors. They’re simplifying the process. Vanguard, a fabulous US-based investment firm, has also spread its wings. Today, people around the world can use their products. This book explains how.

But why should you bother with my book when hundreds of others distill similar themes? To explain, I need to tell you why I wrote Millionaire Teacher in the first place. I used to teach at a private school. None of us were eligible for defined benefit pensions. For that reason, our money had to hum.

When I first arrived at the school, many of my colleagues knew that I was also a personal finance writer. They asked me questions about investing, so I volunteered to give after-school seminars. They were more popular than I had imagined.

But I wanted to deliver more than a handful of seminars. I wanted to find the simplest investment books I could and gift them to my colleagues. So I did just that. I bought 80 investment books that represented 12 different titles.

The next day, I posted an “all school” e-mail. “I have free investment books in my classroom,” I wrote. “Please come and take one.” They got gobbled up faster than cookies in a staffroom. Then, as if I were teaching a group of English students, I met the readers in small groups to discuss what they had learned.

But there was a problem. Many of the terms used by the financial authors were as decipherable as Egyptian hieroglyphics to my colleagues. Too many financial writers don’t realize that much of what they write flies over the heads of the average person.

I told Ian McGugan. At the time, he was my editor at MoneySense magazine. “Write your own book,” he said. But I couldn’t do it alone. I asked for help. More than 100 of my friends and colleagues contributed to the book. Continuing to hold free financial seminars, I probably did more questioning than lecturing to find out what the average person understood about money so I could reach the broadest possible audience.

I shared my early drafts with non-financially minded friends. They all gave feedback, which I used to eliminate jargon and make things clear.

The result is this book: written by a millionaire teacher who listened closely to his students. In it, I share the nine rules of wealth you should have learned in school. You’ll learn how to spend like a millionaire and invest with the very best, while avoiding the trappings of fear, greed, and the manipulations of those who want their hands on your hard-earned money.

I followed these timeless principles and became a debt-free millionaire in my 30s. Now let me pass them on to you.