This is such an important question. There are three things you can do for your kids,

1) Let them understand that asking any question is ok

2) Seeking answers to questions informs you about your world.

3) Anything really is possible with infinite time and money, use those goals as vectors to move your life forward.

In terms of recommendations I was pretty blown away by Buckminster Fuller's An Operating Manual for Spaceship Earth[1] as he has such a great way of looking at things differently and to pull you out of your own preconceptions.

I would also recommend an encyclopedia, because frankly it is a great way to get answers to questions and way less dodgy than trying to figure out good data from bad data on the Internet (not to mention few people have gotten into trouble getting caught with an encyclopedia in their room, which can not be said for an Internet connected computer in their room.)

Understanding how to ask questions, how to test your understanding, how to theorize and make predictions and test those theories. Those are the life skills that turn a bright child into a force to be reckoned with early in life.

[1] http://www.amazon.com/Operating-Manual-Spaceship-Buckminster...

Can't remember which book this quote is from, but "Critical Path" and "Operating Manual for Spaceship Earth" are great food for thought:

http://www.amazon.com/Critical-Path-Kiyoshi-Kuromiya/dp/0312...

http://www.amazon.com/Operating-Manual-Spaceship-Buckminster...