[giancarlostoro]

I used to have PDFs on my Kindle, you used to be able to email them to your Kindle, I think Amazon killed that functionality, I believe you can plug it to your computer and mount it and drop in the PDFs but I don't know if it needs to be in a specific directory, just be weary of image heavy PDFs they may not load at all.

[smokey_the_bear]

I do know how to load arbitrary PDFs onto the kindle, you can do it now with a specific email address that's assigned to each kindle. It's allow-listed for coming from your amazon email address though.

I was not able to extract the PDF from the online textbook. I think I had something that would have worked to just get the content, but I'd have had to stitch all the chapters back together, and if the page numbers didn't match the original book it would have been a hassle for my daughter.