What is a source for Richard Riley's famous quote about preparing students for the future?
Generation Jobless by Peter Vogel has this quote at the beginning of Chapter 3, and attributes it to "Gunderson et al, 2004"

Checking this book's bibliography, we can find that "Gunderson et al, 2004" refers to 

Gunderson, S., Jones, R. &amp; Scanland, K. 2004. The Jobs Revolution: Changing How
America Works. Copywriters Inc

I would suggest you check there.