Google Docs is an obvious choice for this, particuarly since the TDSB provides teachers with Google Apps for Education.
If, however, you are looking for alternative ways, then check the following:
- 15 Free Tools for Storing and Sharing Files (includes brief descriptions of the pros and cons of each)
- Quickly Share Large Files Through Just Beam It (includes description)
- WeTransfer – Transfer Files Quickly and Easily (includes description)