Classify economic activities into the four sectors, calculate GDP per capita, and compare GDP with the Human Development Index as measures of development.
Economic geographers sort every job into one of four sectors. The primary sector extracts raw materials directly from the earth -- farming, fishing, mining, logging. The secondary sector manufactures those raw materials into finished goods. The tertiary sector provides services -- retail, healthcare, education, transportation. The quaternary sector deals in knowledge and information -- research, software, finance, consulting. As countries develop, their workforce typically shifts from mostly primary toward mostly tertiary and quaternary work.
GDP (gross domestic product) measures the total value of all goods and services a country produces in a year. Because a huge country and a tiny country cannot be fairly compared on total GDP alone, geographers divide by population to get GDP per capita -- a rough measure of average economic output per person. But income alone does not capture everything about quality of life, so the United Nations built the Human Development Index (HDI), which combines income with life expectancy and education into a single score. Two countries can have similar GDP per capita and very different HDI scores if one invests far more in health and education than the other.
Mastery looks like: They can correctly classify jobs into the four economic sectors, calculate GDP per capita, and explain what HDI adds beyond income alone.
Common stumbles: Confusing GDP with GDP per capita; assuming a high-income country automatically has a high HDI without checking health and education.