Students may either color or use red/yellow two-sided bingo chips to create the number listed at the top of each page using two different colors. (I used the numbers 4-10 because the numbers 0-3 cannot be made two different ways without using 0). I laminate the pages and have students use dry erase markers. They know that there have to be two DIFFERENT sets of numbers on each page (i.e. 7 and 3, and 5 and 5) or else they didn't do it correctly. They cannot simply change the pattern or switch the colors (i.e. 4 red and 1 yellow, and then 1 red and 4 yellow) because the numbers have to be DIFFERENT from the other side. It's tricky at first, but they get the hang of it, and then they try to trick each other!