I need to replace several keys on our keyboards here at my school (student abuse) but I can't seem to find them on your website. Help!

Apple has supplied key caps for some laptops, but not others over the years. Unfortunately most Apple techs are not aware of this option. As others have mentioned, you would need to contact Apple or an AASP to see if it is possible to replace a few key caps. Keep in mind this still may be expensive since Apple only sells a complete key cap kit which includes a single key cap (and possibly scissor mechanism) for every key on the keyboard.

Sometimes it is possible to get key caps from third party vendors, but you must be extremely careful since Apple typically utilizes keyboards from two different manufacturers for each model laptop (with different model year perhaps utilizing yet different ones yet again) and the key caps & scissor mechanisms are not interchangeable and it can be very hard to differentiate between the two styles as there is very little difference between them.

What generation of Apple keyboards do you have at your school?

see > https://en.wikipedia.org/wiki/Apple_keyboards

With the model # you can begin your Google Search.

see > apple keyboard replacement keys

Optionally salvage keys from non-working units.

This is a user forum, you are not addressing apple here just fellow users

as an institution you may also wish to attempt to contact on a more format channel

Contact - How to Contact Us - Apple

That’s because Apple doesn’t sell keyboard parts. At least they don’t sell them to anyone other than authorized service providers.