I am pretty far removed from having a 9th grader in the house, but I think that most school students would need a word processing app or if your daughter is an MS Office user - apps that offer similar functionality would be a must have for her.
Apple offers their own suite of iWorks apps - Pages (Word), Numbers (Excel) and Keynote (PowerPoint) that are compatible with the MS Office apps. However, it seems to meet with mixed reviews by a number of users on this discussion site. But another highly recommended, popular choice for the MS Office compatibilty is Documents to Go Premium Suite. This app offers all three - word processing, spreadsheets and presentations in the one app. There are other choices in the app store as well.
iBooks would be another must have app. iBooks will read and save pdf files as well as it's obvious use as an e-reader - and the deal sealer - it is free!
Pandora Radio is a nice internet radio app and it is also free. That always makes a nice app even nicer!
All iPads have to have a couple of games on them as well and Angry Birds has been very popular for a while.
That is a start anyway. Other opinions will follow for sure.
thanks for the detailed info, it's almost as if you knew we are converting from windows.
My daughter currently uses word and power point on our home pc for school work therefore pages and keynotes sound like they would be ideal, sounds like I have a little research to do.
Your answer actually covers a similar question I submitted for my other daughter on the ipod touch.
Thanks for the reply, much appreciated.