Is it possible to use this in Canvas and have the student access THEIR SAME copy multiple times for for prolonged assignments? Or, will it create a NEW copy each time they click on the assignment?

If this is something that cannot be repeatedly opened and edited for future uses, without leaving Canvas, then I will create a short document for single use.  

The best case scenario would be that we can operate a notebook for an extended period of time and continuing building the document.