I use this mat to introduce fraction and Mixed number sums with regrouping. This can be used whole group, small group, or as a reteach. I find it especially useful with kiddos that don't quite understand why we regroup. It only has denominators of 2, 4,and 8. I do, however, have the kids create other denominators using the given ones as an extension.
After we use the mat, we go back and work the equations arithmetically so that kiddos can see how the model relates to the "math".
Let me know what you think!