A rubric is simply a way to assess something by breaking it down into its component parts, and weighing them according to the importance of that part. For instance, a rubric for evaluating a writing assignment could include a breakdown of items to be considered such as grammar, APA style, structure/layout, introduction, body, conclusion. These would all be given different points possible relative to the overall importance of that item to the whole, e.g. grammar might only be 5% whereas the Body might be 25%. In effect, a rubric is a way to evaluate something by looking at its component parts.
As you probably are aware there already exists an evaluation form to use for student presentations. This is located in the Resources section of the Faculty Orientation Canvas Course and on Blazenet under Faculty Resources/Adult and Graduate/Documents. The link above takes you to the Canvas course but you can find the evaluation at either location.
What I have found to be extremely useful as an activity a week or two before the presentations are to be made is to distribute the evaluation form to the class and engage them in a discussion about the weight of each of the items, whether there should be more or less items, and how the evaluation form might be modified for their upcoming presentation. The Instructor, of course, needs to protect the points awarded in the content area, but this activity has tremendous power to increase student buy-in and awareness of how the evaluation will be assessed. Typically you can conduct this activity in about 30 minutes and it also gives the opportunity to discuss the assignment itself and answer questions.
Going a step further, on the day of presentations, have students evaluate each other using the rubric they created, and use those evaluations when considering the final score. By doing this you not only emphasize the importance of the subject, but the importance of the presentation itself, which is also a learning objective of the program, if not the course.
Having students create their own rubrics teaches critical thinking skills and make them part of the learning process. Give it a try and let me know your thoughts.