This page might help you determine what is “fair use”. http://en.wikipedia.org/wiki/Fair_use
The example about copying a spcific pattern from a book is because it is one short excerpt from the book, for non-comercial use and doesn’t damage the copyright owners ability to sell more books.
Excerpts of all kinds of things- writing, music, etc have long been copied for educational purposes and this often falls under the “fair use” exception to copyright laws. Also, copyright expires after a period of time. Depending on the country, the duration of copyright is typically the whole life of the creator plus fifty to a hundred years from the creator’s death, or a finite period for anonymous or corporate creations. So many of the older books an things are copyright free already.
The best source might be to ask the librarian what exactly is allowed with the specific materials you check out. You always have the option of renewing if 3 weeks isnt long enough. 🙂