Teachers, as well as others, collect materials from differing sources. PDF is the ideal format to consolidate all types of printable material on your computer: it gives an exact representation of a printed document on any system, integrates well with Google Drive, and can even be saved on iPhone and iPad. You may already be using a copier to scan physical papers to PDF. By using a PDF writer such as CutePDF, you can print to a PDF file without using any paper. This way, you can eliminate many technical issues and make sure people on different systems see the exact same document.