Posting an item to Electronic Course Network - ECN (formerly Sakai) does not exempt an instructor from copyright regulations. Therefore, instructors are encouraged to follow copyright "best practices." In order of preference, these include:
Link to your article from a library database.
If linking is not possible then consider making a print copy of the article for your class.
When all else fails, complete a Fair Use Evaluation, scan your article, and then upload it to ECN.
Fair use does not allow for repeated use over multiple semesters (rule of thumb is: more than 2 you should request permission). For repeated use you will have to contact the publisher and request permission.
Please see the Copyright Guide for more information, including some permission letters.