Apple has no general program for donations of either money or product. You can write to Apple at their corporate address - click the Contact Us link at the bottom of this page - and ask, but I doubt you'll get anything but a polite refusal if you get any response at all. You will probably have the best luck if you contact charitable organizations and businesses, such as independent Apple dealers, in your own community. Those organizations will be in the best position to assist and would be the ones most interested in helping charities and programs in their own communities.
Good luck and regards.
Hi, have you looked at Donors Choose? I previously worked at a school and teachers were able to get a lot of technology donated through this program. You need to make a compelling case to attract donors and it may help to start small and work up to the full set of ipads you need/desire. E.g. you may want to ask for a device or to to start or even start by asking for donations other than ipads first to build up a history before asking for the ipads. Donors choose does have a price limit for first time requests to help prevent abuse of the program - I'm not sure what it is, but you'll have to look into that.
I'm not sure of your situtation, but high-needs and urban classrooms do tend to get the most donations.
Good luck and I hope you are able to get things to help your students.