"NASA Education is launching a new website to get students and educators off the launch pad and on their way to becoming rocket scientists."
NASA - Rocketry has sets of articles designed for kids in grades K-4 and 5-8 on topics like What is a Rocket? (this is the K-4 version) and What is the Space Shuttle? (this is the 5-8 version). You can compare the designs of model rockets and their full-size counterparts. (I've got to admit, the interactive flash version of this article is more fun!) You can even build your own rocket, but, alas, it's only online. Through NASA Kids' Club, you can build an entire fleet of online rockets with Rocket Builder.
Thinking of a career in rocketry? Read the bios of these engineers and scientists. Learn about educational opportunities like Rocketry Workshops for grades K-12 and the Team America Rocketry Challenge.
The NASA-Rocketry website has also compiled a wonderful collection of podcasts, videos, images, and simulations at their Robotics-Multimedia page. That's where I found this:
Photo credit: NASA