Do you want a fun fraction center for your students? This is a document I use for the students to keep track of their fraction cubes. I have fraction cubes that have images of fractions on each side. The students roll the cubes then use this document to compare the fractions. This allows them to visually see the fraction on the cube while comparing.
For a more abstract center (higher grade levels), you can also have them roll the cubes and put the fractions down on all questions then go back a