Help children to be successful. Experienced providers can tell each child's frustration threshold. Step in right before a child is about to give up on a problem. Give a small hint or a bit of encouragement to help a child be successful. Allow failure sometimes.
Failure can be good feedback.
When the block falls, the child learns that he must balance it more carefully or select a smaller block. Be careful, some childen need every chance for success they can get. Be willing to assist these children more quickly. Notice strength and ability in girls as well as in boys. Also, be sure you notice boys being gently, nurturing, and caring.