I've had a class set of iPads for a few years now, and one of the questions I get from people has to do with the students using the keyboard. Overall, this is not an issue for the majority of my students. However, there are some students who need a physical keyboard to use with their iPad. I have found one that has worked great with my students.
The Griffin Wired Keyboard for iOS Devices is a great addition to the iPad for people who need a physical keyboard to get their work done.
The keyboard comes with the older dock connector or the newer lightening connector. I was worried that it might not be compatible with the iPad 2, but it worked great. My students have been able to use these keyboards with their iPads without a problem. For the note taking students do on Evernote, the keyboard has been very important for the students who really needed them.
Some people do not like the wired aspect of keyboards and prefer the Bluetooth connections, but those will drain your battery and will sometimes have connection problems. The wired keyboard from Griffin is a perfect solution for my classroom because I do not have to worry about batteries or connections. Students come in, grab their iPad, grab a keyboard, and get to work. After a couple of weeks, the only problem I have seen is that I do not have enough of the keyboards for the class.
The device is a traditional keyboard with all of the buttons in the right spot and it feels like any other keyboard. I have been able to type very quickly and move around the keyboard like I would on my desktop. Sometimes smaller keyboards will have buttons that are too close together for my fat fingers, but everything feels just right on this board.
At $59.99 for a keyboard, it might be a bit pricey for a class set, but for a few in a classroom where some students will need one, it is an excellent investment. Check them out here if you are interested in getting one for you and/or your classroom.