Leveled reading for learning about astronomy. Sponsored by NASA and has a lot of good information if you have a child interested in this topic or you are studying this in a content area.
Another tiered science website with beginning, intermediate, and advanced levels. It covers three main topics: our planet, our solar system, and our universe. There is a TON of information on this site...I'm sure you could connect it to something you are learning in science!
This is another teacher's website that I learned of last year when taking the district's guided reading class. I linked you to the genre page, where it gives fun ideas you can try to teach kids genre. However, take some time to look around her whole site-there are lots of good ideas and resources!
This is an online tutorial on basic paragraph writing. I think students could go through it on their own or with an adult. It is easy to follow and the graphics make it fun!