Take it easy; you don't have a little Marion Jones on your hands. You have a 3-year-old, and cheating is something that 3-year-olds do. Maybe it's because they don't really understand the rules. Or pieces get moved farther than they should because a 3-year-old's attention span is about as small as the game piece. Or it's just because you gotta make the "right moves" to win, and it feels good to be a winner! In any case, your child is too young to fully understand the concept of cheating and its consequences, so don't get yourself too worked up over it.
To encourage fair play, applaud her when she makes the right moves, and calmly explain the rules when she breaks them so she starts to understand how the game is played. Or better yet: Try playing games just for the fun of it, instead of playing to win. Spending that quality time with you will make her feel more like a champion than a million wins.
Denene Millner is a mom of two, stepmom of one, and a former editor at Parenting. She's the author of ten books.