Both are media that allow multiple authors to write and present material on a web page such that others can add to that written material. Blogs often have comment boxes enabled, so that readers can comment and address the topic which the author has chosen. In a wiki, the original author swiftly becomes the co-author of all pages as readers turn co-author and edit the original page and writing done by the original author. Blogs are more conducive to single authorship and discussion of a topic, whereas wikis are better set up for collaborative work. Wikis allow authors to create new pages for new topics, which might better organize certain kinds of material, rather than the temporally updated and listed material of a blog.
Time as a Factor
With blog, teachers would be able to clearly see when students authored and submitted their work. The general set up of a blog post includes the time and/or date of the post in the header with the title of the post. Wikis are set up to be topic-based rather than chronological in their layout, so authors of the page can edit and change material anywhere on any page at any time on any topic. It is much harder to tell what was done when by whom, unless you have a system that tracks changes. A project with a particular due date for some kind of completed or substantial amount of material would be harder to monitor temporally.
Monitoring of behavior
In a classroom/educational setting, the subject of safety and behavior monitoring have to be taken into account. The natural set up of blog seems to make this easier, as a single administrator can have the power to edit or delete inappropriate posts by authors. It would also be much easier to tell which author posted inappropriate material. Wikis are naturally set up to evolve and change as the group of authors decide, with less attention paid to authorship. This would make it more difficult to monitor the behavior of individuals, again, without the close monitoring of tracked changes. Also, the nature of a wiki is to expand topically. Authors can create new pages and expand the size of a wiki site very rapidly, which is good for material organization, but also makes it easier to hide inappropriate material as a wiki rapidly grows.
I think that choosing a blog or wiki will really come down to assessing what kind of project is being done and what kind of material is being approached. If the material involves a broad topic with many sub-topics that need to be discussed and addressed by all students, particularly in the creation of some kind of study-guide or reference website, then a wiki is probably the best choice. If the students need to turn in distinctly individual materials on a schedule (daily, weekly, monthly), then a blog is probably a better medium. When taking the behavior of a particular class into account, if a teacher needs to monitor and restrict information sharing and authorship more closely, a blogging format and set up with naturally serve better. If a teacher is leading a mature group of students in a project that is understood as a peer editing and collaborative project, then a wiki is an exciting resource to be able to use.
This post is part of the 21st Century Learning post series.