Hello dmiller 
Welcome to the Canvas Community. Thank you for posting your question. @rmurchshafer is correct that the current Canvas interface currently doesn't have a way to upload a rubric to an assignment. However, I do have some good news for you. A fellow Community member, @James , has developed a way to create a rubric via an Excel spreadsheet, and then you copy/paste the rubric from the spreadsheet into an interface he created inside of Canvas. I've used his method countless times, and it has literally saved me hours upon hours of work building courses for our instructors. James' tool is commonly known as a "Canvancement" here in the Canvas Community. It's not part of the core Canvas product, but something he built on his own and has shared with others. So, I would invite you to check out all the details here (including a thorough explanation of what it does, screen shots, and short tutorial videos): Importing Rubrics from a Spreadsheet. I hope this resource will be helpful to you, Doug. It certainly has been for me!
