I put my students into different math centers and one of them is an independent group. I differentiate the center by using three levels of questions that I name by color: red, orange, and green. The red is more basic, orange steps it up a notch, and green takes it a step farther and is more advanced. I have a sheet that is in the center's bucket that has the students' names listed under the red, orange, or green column. I cut up the cards and have 9 red, 9 orange, and 9 green cards and they each go in their own ziploc bag. The students know which bag to use based on where their name is on the sheet.