I have always heard academic rigor in the context of having high expectations for your students. If you have a rigorous curriculum, then the students are expected to learn quickly, perform well, and study material in-depth.
Mrs. Silvio, I looked up the definition to help you. Academic rigor means the consistent expectation of excellence and the aspiration to significant achievement. I think it can be accounted for by having high standards that are achieveable by the students, and not settling for less than you feel they can accomplish. Obviously, easier said than done!
High expectations. Like the previous poster said easier said than done. How about acedemic motivation. Now that's a tough one. It seems that student motivation is getting more and more impossible to accomplish.