That is a great question! Be sure to offer the child plenty of snack choices and explain that outside of snack time, snacks are out of limits. Create a reward (not food-related) and punishment system around this problem. For instance, you can tell the child that if they exercise good self control and do not dip into the snacks you will play a board game with them and if they do they will have to sit in time out. For some children the temptation is too much to handle and a policy of “out of sight, out of mind” is best so consider asking the parents for permission to hide or lock away the snacks until their return.