Get yourself a copy of "Getting Started in Electronics" (W5YI : Product : Getting Started in Electronics) by Forrest Mims. It's an older book, first published in 1983 by Radio Shack, and it is currently being sold by The W5YI Group. You can sometimes find original used copies for cheaper on Amazon. It is written for all ages and uses great hand-drawn pictorial diagrams to describe exactly what goes on in electronic components.
I got my copy of this book in 1985 when I was 10 years old and started playing with electronics, and I haven't stopped yet. I can trace the beginnings of my career as an electrical engineer directly to that book.
It does not cover microprocessors but you will get a great start on basic electronics with this book. It does cover digital logic and TTL and CMOS integrated circuits which you will no doubt run into when you work with microprocessors though.