Ask your students to imagine life without fast-food French fries or potato chips. For us Americans it's only one food, but still one that would be strongly missed. For the Irish of the 1840's, potatoes were almost their only food, and economically their only source of income. A potato disease and the ensuing failed crops cost a million people their lives. More fled the country to emigrate to America.
History repeats itself.
A major famine is occurring now in North Korea. Relief efforts often bog down in state and international politics. World Vision is a non-profit Christian relief service dedicated to eradicating world hunger. Incidentally, the organization was started in the 1950's to bring relief to children orphaned in the Korean War. This is a world-wide effort that engaged a million teens from 21 countries this past February.