Borrow this book from the school library! Perhaps it's odd for a Physics teacher to start with a Biology book, but, honestly, you'll really like it!
Steve Jones is a famous Biology professor. Evolutionary genetics is his specialist subject. This book was written 20 years ago. The first bit is a little out of date - as he predicts, the human genome was mapped. But I was captivated by the rest of the book. It is an account of the evolution of the human species. I was amazed by ideas such as that which suggests that all Europeans are decended from just 4 females. I'm after an update on this research now.
Borrow the book. Try it. If you don't like it, just take it back. What have you got to lose?