Use latitude and longitude to locate and describe places, and explain how GPS, GIS, and remote sensing extend traditional mapmaking.
Latitude and longitude form a grid that pins down absolute location anywhere on Earth. Lines of latitude (parallels) run east-west but measure distance north or south of the equator (0 degrees), from 0 at the equator to 90 at each pole. Lines of longitude (meridians) run north-south, pole to pole, but measure distance east or west of the Prime Meridian (0 degrees), which passes through Greenwich, England, running to 180 degrees in each direction. Give both numbers -- latitude, then longitude -- and you have named one exact spot on the planet.
Longitude also controls time. Earth turns 360 degrees in 24 hours, so each 15-degree band of longitude is roughly one time zone, one hour apart from its neighbors. Travel across the International Date Line, near the 180th meridian, and the calendar date itself jumps a full day.
Three modern tools have transformed geography since the late twentieth century. GPS (Global Positioning System) uses a network of satellites to calculate your exact coordinates in real time -- the technology behind every phone map. Remote sensing collects information about Earth's surface from satellites or aircraft without physically touching it, tracking everything from crop health to deforestation to storm systems. GIS (Geographic Information System) layers many kinds of data -- roads, elevation, population, rainfall -- onto the same map so a geographer can see how they relate.
Mastery looks like: They can read and state a location's latitude and longitude correctly, reason about the time-zone and climate implications, and pick the right geospatial tool for a given task.
Common stumbles: Mixing up which grid controls climate versus time; forgetting to state the N/S or E/W direction, which changes the location completely.