| A | B |
|---|
| percentage of land where people live | 30% |
| percentage of people that live in cities | 50% |
| population density | the average number of people per square mile |
| biggest challenge of growing populations | providing enough food |
| demography | the study of populations |
| metropolitan areas | city and surrounding areas |
| migration | movement of people from one place to another |
| refugee | people that leave their country because of bad conditions |
| what causes people to be refugees | war, food shortages, natural disasters |
| culture | way of life of people that share common beliefs and customs |
| the most important social group | the family |
| 2 ways governments are organized | levels of power and type of authority |
| what caused the rise of cities | extra food |
| information revolution | the use of computers |
| what causes populations to change | births, deaths, migration |
| ethnic group | group of people who share a common language and history |
