Addition, subtraction, multiplication, factors, odd/even...you choose the skill or skills students will practice with TRI-NUMBERS. Students join the colorful triangle cards according to the criteria you choose. For example: numbers with a sum of 10, numbers with a difference of 2 or 3, numbers that yeild an even sum, numbers that yields an odd product, numbers with 5 as a factor...use one or more of the 24 criteria choices given, or use the blank cards to write your own. Students may work with 0-10 numbers, or add the 11-20 cards. TRI-NUMBERS can be used as a single student or group center, or played as a game. Both full color and black & white versions are provided.