The rows and columns for Blackboard Rubrics have default headings which you can easily change to meet your course needs.
Start out in the Create or Edit Rubric window.
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Under the heading Rubric Details should be the Rubric Grid with all the default rows (Criteria) and columns (Levels of Achievement).
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Next to any row or column heading, click the gray arrow and Edit. Type your new title and click Save.
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Be sure to click Submit to save your work.