You can allow students to create a new discussion by changing the settings from the Discussions page. When this setting is enabled, discussions created by students become part of the course and are included in future course copies and exports unless the discussions are deleted.

The course discussion student setting can also be changed from the Course Settings page.

Note: 

• If a student creates a discussion that includes a file, the file will be added to the unfiled folder in course files.
• If there are no discussion submissions, you can edit the anonymity details.
• If a student has a section restricted enrollment in the course, the student can only create a discussion that will be posted for all users in the course. You can still create groups, and students within those groups can initiate discussions that are visible only to their group members.