Reddit mentions of Cosmology: A Very Short Introduction

If you want to go the self teaching route there are some great books you can get. A nice introduction is: http://www.amazon.com/Astronomy-Self-Teaching-Guide-Wiley-Guides/dp/0470230835/ref=pd_sim_b_1

Beyond that there's this book: http://www.amazon.com/Astrophysics-Easy-Introduction-Astronomer-Practical/dp/1852338903/ref=sr_1_1?s=books&ie=UTF8&qid=1367595032&sr=1-1&keywords=astrophysics+is+easy It gets way more in depth. This book will leave you with a really great understanding of the universe.

It looks like about.com has a free intro to astronomy course: http://space.about.com/cs/astronomy101/a/astro101a.htm

I haven't gone through this course but poking through it it looks like it covers a lot of information.

Something I do to stay on top of current astronomy issues is read Sky and Telescope magazine and check out space.com and universetoday.com, sometimes I'll run into concepts that I'm not very familiar with and that's where wikipedia helps out.

Let's say you read an article talking about how old a star in a globular cluster is and you're like "what the hell is a globular cluster?" and you haven't read about it in one of your intro to astronomy books, well, bam: https://en.wikipedia.org/wiki/Globular_cluster

The books that are regularly considered the best introductions to skywatching are:

Nightwatch by Terrence Dickinson

Backyard Astronomer's Guide by T. Dickinson
and

Turn Left at Orion by Guy Consolmagno and Dan M. Davis (you must get this book if you buy a telescope)

Below are some other great books that get much more in depth on the astrophysics side of things.

http://www.amazon.com/Briefer-History-Time-Stephen-Hawking/dp/0553385461/ref=sr_1_1?s=books&ie=UTF8&qid=1367595413&sr=1-1&keywords=a+briefer+history+of+time

http://www.amazon.com/Cosmology-Short-Introduction-Peter-Coles/dp/019285416X/ref=sr_1_2?s=books&ie=UTF8&qid=1367595478&sr=1-2&keywords=cosmology

I love it! When I worked at a library, I used to take this little book off the shelf and secretly read it in the stacks.

It may be too advanced for a second grader, but maybe you'd enjoy it and be able to relate to your daughter things you learned from it, and when she's a bit older, read it herself. I thought the description of general relativity in here was really well done, and fascinating (plus it's only like $6).

Edit: Oh and if you haven't already, watch Through The Wormhole and other physics/astronomy documentaries.

The Feynman Lectures are a perfect introduction to physics from high school level all the way up to degree level.

A good understanding of maths is essential to more advanced physics and there is an excellent textbook written by two extremely qualified headmaster's called The Language Of Physics: A Foundation for University Study which is what's recommended to first year University students and poses questions at the end of each chapter.

If you're looking for something a little less intimidating, then the A Very Short Introduction series have a perfect range of short (and cheap!) books on Physics: [Quantum Theory]
(https://www.amazon.co.uk/gp/product/0192802526/ref=pd_sim_14_4?ie=UTF8&psc=1&refRID=9A3MSV2XSQRYF880MYP6), Relativity, Particle Physics, Cosmology, Nuclear Physics, Black Holes, Thermodynamics, Astrophysics, Light and Magnetism. These are great little books that don't blow your head off!

Physics is an extremely interesting subject to read around and I wish you the best with it :)