Your daughter is not allowed to have an iPad... when I was in 3rd grade, I had a Commodore 64!
Seriously, though... I like the idea of a Mac mini. I have one hooked up to my LCD TV in the living room. It is my main computer, as well as being part of our entertainment system. I have a monitor in the office that I can hook it up to if I want to use it away from the living room... which may be a nice option for you, since you will probably want to watch TV at some point while your daughter is working on something for school. The mini is VERY easy to move from one place to another. You might want a power cord in each location to make it that much easier. Having a wireless keyboard and mouse makes it super portable.
I only wish that there was an EASY way to use my iPad as a screen for the mini. I can do it with my remote access app, but it is going over wifi, so the refresh rate is far too slow.
Someone also mentioned that in order to print from an iPad, you would need a printer that is air print capable. I have one (HP Photosmart c410a), and it is fantastic! It works wirelessly (wifi) between my wife's Windows notebook and my mini, and also works great with my iPad and both of our iPhone 4s. Another thing I like is that it is an all-in-one machine, so it will scan, too... and can scan to either computer wirelessly. It won't scan directly to the iPad or iPhone, though.