She’s about to turn sixteen, if that matters. Interested in science but not a genius so far as I know. This is what she wants for a birthday present.
What kind of science? Biology? Physics? Geology, astronomy, natural history?
She specifically said “science” and didn’t want to be pinned down further, but I suspect her biggest interests are in biology or ecology.
She would probably enjoy many of Jane Goodall’s books, then. I read Through A Window when I was fourteen and just loved it.
Not biology or ecology, but most of Carl Sagan’s stuff is great. His Contact could be perfect for a teenager so long as she doesn’t mind (soft) SciFi.
Of course, if SciFI is allowed, there is only one choice for a youngster - the Foundation Trilogy by Isaac Asimov. Changed the lives of a number of people I know (including yours truly).
Getting away from science fiction and focusing on ‘science’, everything by Simon Singh that I’ve read has been excellent and very readable.
Surely You’re Joking Mr. Feynman, although that’s about the man more than the science. Also not biology.
I enjoyed the Selfish Gene. A know of lot of Dawkins’ books are explicitly atheistic; is The Greatest Show on Earth? If that wouldn’t matter either way, try him out.
Here are a few nonfiction science books I’ve liked recently…
Thinking in Pictures by Temple Grandin - includes some stuff about the author’s teenage years that I think would be interesting.
The Greatest Show on Earth by Richard Dawkins - I found myself totally immersed by this book and couldn’t put it down, and I’m not that science-minded, myself.
Quirkology by Richard Wiseman
Why We Buy: The Science of Shopping by Paco Underhill
Another vote for “Surely you’re joking, Mr. Feynman”. There’s not real science in it, but it’s about science and is a very fun read.
I’d recommend Stephen Jay Gould’s stuff. A lot of them are essay collections, so they’re easy to pick up & put down. Some of his stuff is a little outdated (that dern science, always changing!) but good basics and very readable.
I started with “Hen’s Teeth and Horse’s Toes” and got completely hooked. “The Mismeasure of Man” ought to be required reading for everyone.
Michael Pollan’s Botany of Desire, about the coevolution of various plants and human beings. The “desire” in the title refers to humans’ desire for sweetness (apples), beauty (tulips), intoxication (cannabis), and control (potatoes).
Not sure if the third section would create problems with her parents or not. 
I enjoy Martin Gardner’s Fads and Fallacies in the Name of Science. For that matter, anything by Martin Gardner would probably be good.
How about a biography of somebody like Da Vinci, Einstein, etc? Maybe Marie Curie for the female thing…
Okay, this is a really random assortment of stuff, not really hard science but dependent on science.
Lewis Thomas’ * Lives of a Cell* is a beautifully written set of essays about biology.
Diane Ackerman’s A Natural History of the Senses; there’s science here but I think it would go especially well with a teenager’s intense experience of the sensory world.
For science fiction, long before I had any training in genetics or molecular biology, I loved reading about genetic engineering in Octavia Butler’s Xenogenesis series. CJ Cherryh’s Cyteen series really gets into the psychological and political effects of genetic manipulation.
If she has any interest in medicine, both the Anatomy Coloring Book and the Physiology Coloring Book are nice and easy for starting to learn about the body. I also like the Anatomy of Movement, with great drawings that show what parts do which movements, nice for learning about exercise and injury.
Mary Roach’s Stiff gets into all kinds of funny details about death and cadavers.
hands down
*Physics and Technology for Future Presidents: An Introduction to the Essential Physics Every World Leader Needs to Know * is an excellent book.
It can be found here:
Another vote here for Feynman. I WAS a teenage girl (although several decades ago) who enjoyed reading about science and whose family was very into the subject as a whole. Though it’s mostly NOT about science, the book is chock-full of his sheer love of the subject.
Any of Oliver Sacks’ books could probably be read by a smart teen. At that age, I also loved the compilations that were available of Berton Roueche’s real-life medical detective stories. I think one compilation is still in print under the title “The Medical Detectives.”
Another suggestion - why not get her a subscription to one of the more accessible science magazines that she can enjoy every month? I’d suggest Discover, because they cover a broad range of sciences and are interesting.
Hope this helps!
Guy Murchie The Music of the Spheres
I actually think the movie is far superior to the book.
She likes biology and ecology, does she? Can’t go wrong with Tuf Voyaging by George R.R. Martin, about a guy who finds a long-abandoned starship with awesome ecological-engineering capabilities and goes around to different planets, renting his services. Funny, witty, thought-provoking and a helluva read.
Does she like manga? I’ve seen these at Fry’s–can’t vouch for them, but O’Reilly does a lot of geek books.
Have you already given her Heinlein’s juveniles? Because, while much of the science is outdated, they’re still darn good stories, and Heinlein does a good job of instilling an interest in and respect for science. Although it sounds as if she already has that, which is good.
I don’t know if they’re "science"y enough, but Jared Diamond’s books Germs, Guns and Steel and Collapse! are quite good. Maybe a little weighty for a teen.
Another vote for Bill Bryson’s Short History of Nearly Everything.
I think Richard Preston is great. Get her The Hot Zone if you want to give her nightmares, or The Wild Trees, which is about redwoods and people who do free-climbing.
If she’s socially conscious, she might like Barbara Kingsolver’s Animal, Vegetable, Miracle. Kingsolver’s teenage daughter figures prominently in the book as a contributor of recipes, etc.