When you want to copy documents from the Blackboard course that has been placed in Brightspace to the Brightspace course, you do this in the same way as explained in this article: How do I copy content from my Blackboard course to Brightspace? You then choose the Course Files option after selecting Components and select the correct files or all files. Below you will find further instructions.
Click on Course Admin in the navbar and then choose Import/Export/Copy Components.
Click on Search Offering and search for the course from which you want to copy the files.
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Check the course and click Add Selected.
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Then click Select Components and check Course Files in the list. You can now choose to include all Course Files or select specific ones.
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If you choose Select individual items to copy, you will see a long list. Look for the course files. You will need to expand this several times before you reach the documents. Select the files you want to copy and click on Continue.
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Then click Finish. The documents will be copied. Once the copying is complete, you can find the documents under Course Admin > Manage Files.