Students may continue their development of analytical skills by identifying the costs of their decisions. They should recognize that a cost is what is given up in gaining something. This fits with the economic concept of exchange. When students trade, they gain something, but they also give up something. What they give up is the cost of the choice. It should be emphasized that each choice has a cost (a simple example is the story of the Three Little Pigs, where two of the pigs give up safety for play)