Students have a 100s board and red/yellow counters. They pick a card, cover the number. After about 12 cards- they have an "answer" board that they can check to see if they have the right numbers covered. I have 3 sets of cards- the first set just practices 1 more and 1 less for numbers 1-30. The second set practices numbers 1-50 with up to 5 more or 5 less. The last set is for numbers 1-100 and works on more, less, 10 more, 10 less for those more advanced kids.