These flashcards are designed to be able to print as double sided cards, with one addition fact on the front and the related subtraction fact on the back. In this way, students can learn about the three numbers within the fact family. Near doubles are based on knowing the double facts - they are one more or one less than the double fact (ex. 4+5 = 4+4+1 = 8+1 = 9). Facts go from 0+1 / 1-0 to 9+8 / 17-8.