When using iPads in the classroom, not every site works as anticipated. iPads do not do flash or java applets, so if you send the kids to a site that relies on flash or java, it won't work. I discovered that one day when I sent kids off to a virtual manipulative web site. It didn't work so I hurriedly readjusted my plans. I did research and discovered the iPad's limitations. So off I went to figure out how to do what I wanted to do without pulling my hair out.
First thing I did was go to the app store to check things out. I found Rover which is a browser designed to be used by k-12. It is actually a cloud based flash streaming platform that allows iPad users to access flash based websites. It is a bit slow at times but it allows students to access more sites than in the past. It may run a bit slow for me since we sometimes have bandwidth issues and that often slows down all internet usage.
I do have to try the web page in the web browser on the iPad to see if it works. If not, I go to Rover and if it works, great, if not then I look for alternate sites.
One website I use quite often is www.mathisfun.com It has pre-algebra, algebra geometry and algebra II materials. One reason I like it so much is that in addition to explaining the material, it also has a quiz to go with most of the topics. I can have the students take the quiz, write down their work and answers and turn it in.
The thing about the iPad is learning what works and what does not.