Convert from Illustrator to a new program

Were the Illustrator files created with the PDF compatibility option enabled? If so that might open up more options. Adobe Acrobat might be able to assemble multi-page PDFs from those files, but that's another Adobe application.

It's possible for some rival graphics applications to import Adobe Illustrator .AI files and PDF files. But there are limitations. None of Illustrator's rivals cover all of Illustrator's features and effects. That could lead to certain artwork elements being altered when importing the file. Once the file is imported into that rival graphics application will the file be saved in that application's native format or some other format? PDF files have a great deal of widespread support, at least for document viewing and printing.

What kind of project are we talking about? A curriculum? What does that consist of? text? graphics?

Generally there are no good solutions for your task. You have no idea which new application you want to use? If it is a text based publication, InDesign would probably be the better choice. But depending what kind of publication it is, switching would most probably mean rebuilding the whole thing from scratch. You can open and then edit PDFs in some layout apps, but the kind of file you get is less than desirable.