In the real world, meeting the needs of one individual often has negative consequences for someone else. In this video segment from PEEP and the Big Wide World, children see that their dam design does a fantastic job of stopping the flow of a stream of water, but it also deprives their friend of the water supply he needs to maintain his own pool of water downstream. By assessing their individual needs and the needs of others, the children use engineering design principles to create a solution that gives them all something to celebrate.