Free E-books in PDF format are the essential element of a low cost curriculum.
Open source or royalty free e-books provide course textbooks for instructors and students alike. As a vocational electronics instructor, I had to teach armed only with a blackboard and a class textbook. Today, a student can be given not only the class textbook but a small library of books that can be stored on a single stick (flash drive) for a lifetime in PDF format. The PDF format is not only a popular format fordispensing free-ware, but is a format that will be supported for a century. I say this because this format is used for real estate, legal, and business documents that will still need to be read one hundred years from now. The list of free e-books below are just a sample of the huge collection of publications available free on the Internet. The mission of this site is making teachers aware of this collection of copyright free e-books that can be downloaded at no cost. Once downloaded an instructor can distribute them to student computers via the USB port. Students can then study them at home even if they have no Internet service. Even students from homes without electricity could use battery powered laptops and study in the dark.
Math and Algebra
My WEB provides a free virtual electronics laboratory for any science instructor or school that lacks a real or even a virtual laboratory. My site is the best if not the only site whose focus is on on circuit troubleshooting.