I love this article, and now I can't find it anywhere on the web. So I've put it on scribd*. (There are permissions at the end for copying it.)
I was inspired to put it online by a discussion on the change.org education blog, about Sudbury schools. Someone asked about math, here's the answer.
*There are permissions at the end for copying it, so I know it's legal. But the folks at Sudbury school aren't comfortable with the fame this piece has gotten. So many people focus on this: "I found a book in our library, perfectly suited to the job at hand. It was a math primer written in 1898." And they want to know what book it was. But the book wasn't the important part of this story. The kids' choice to delve in was what made it work.
I asked for permission to include this piece in my book, and they wouldn't give it. So in the book I explained the important parts of the incident, and included a short quote.