It is actually OK to copy other people's work as long as you:
- Use only a small part compared to your work (proportional)
- Are using it to say something original or comment on the work
- Cite the work
- Aren't making money off of it or causing the creator to lose potential income
All of these requirements make it safe to use other people's work ESPECIALLY IF YOU ARE USING IT FOR EDUCATIONAL PURPOSES
Cases have defended using fair use guidelines for educational purposes as high as the U.S. Supreme Court.