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This tool (Open University blog) allows students to blog within a course and share their postings with the instructor AND other students enrolled in only that course.
The OU blog tool is added to the course by the instructor by using the "Add an activity or resource" option (with editing turned on).
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Online text tool in assignments
The "online text" tool in course site assignments allows a student to blog privately. Only persons with the Instructor or TA role in that course site will be able to access these blog posts.
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