This feature is used to create a recurring assignment. If a teacher wants to grade daily participation, they can create an assignment for participation, and select "Create Multiple Instances Of This Assignment" in the assignment settings. 

They can then set a date range for the assignment to repeat, and on which days (ex. every Monday through Friday, for the marking period or year).

This will then create an assignment on the days selected, through the date range selected. This prevents teachers from having to enter in repeating assignments (daily participation, weekly quizzes, etc) individually.

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