Overview6 copies each of all three reading levels, 18 books total. Food Supply examines the challenges of feeding a world that is home to more than 7 billion people. Every day, nearly 1 billion people go hungry. The causes of food shortages include crop failure, soil depletion, flood, drought, and poor food distribution. To address these issues, many aid groups are developing strategies to increase crop yields. Food Supply explains how different countries are meeting the challenges by using a variety of measures, from better fertilizers to improved education for farmers.