This is for learning purposes as I am an instructor and I don't want to buy hard copies of the books. It is much easier to purchase ebooks to share.
Intellectual Property Law Attorney
Generally no, that is copying, distributing and is an effort to cheat the publisher. It will likely not be fair use the way you describe it. Your students can buy Kindle ebooks if cost is an issue or can go to the library. Of course it's easier to commit copyright infringement. Is that what you want to teach your class to do?
I am not your lawyer and you are not my client. Free advice here is without recourse and any reliance thereupon is at your sole risk. This is done without compensation as a free public service. I am licensed in IL, MO, TX and I am a Reg. Pat. Atty. so advice in any other jurisdiction is strictly general advice and should be confirmed with an attorney licensed in that jurisdiction.
I agree with Attorney Burdick, you are describing straight up copyright infringement. There is an exception that may be applicable if this was within the context of a non-profit educational institution and done within the classroom learning environment. Merely saying it is for learning purposes does not get you there.
If you have any doubts, I suggest that you consult with a lawyer in private and discuss your objectives in more detail. You can start by calling around to several for a free phone consultation, get some insights then pick the best fit to work with.
DISCLAIMER: this is not intended to be specific legal advice and should not be relied upon as such. No attorney-client relationship is formed with the law firm of Natoli-Lapin, LLC on the basis of this posting.
Patent Application Attorney
As my other colleagues have noted, you should not purchase a book and share it with others. Using the material for a class is generally okay as fair use, but putting the content out for others to copy without paying for it is likely an infringement. You may couch this as a learning purpose but you have just betrayed your aim by desiring an ebook so you can share.
This is not a legal advice as I do not have an attorney-client privilege with you. You should retain a lawyer before acting on any generally available advice.