A great introduction to online projects is a unit that can be completed offline. Paper blogging over a week (or shorter) if necessary can teach many digital citizenship skills including staying safe and quality commenting. Descriptions of this project can be found in the following blog posts.
Best lesson description I've come across: http://www.notesfrommcteach.com/2010/09/learning-to-blog-using-paper.html (also pdf in Drive in case disappears)
Blogging scope and sequence: https://docs.google.com/document/d/1RIxA7kRSkT-eEPNtsIyxFehS4AIm1UtFzAhhPmKVCfk/edit
Sample lesson plan: http://bookwyrmish.edublogs.org/paper-blog-lp/51/
Mrs Yollis' blogging resources: http://educational-blogging.wikispaces.com/