Geography · 7th Grade · The Geographer's Toolkit · Weeks 1-9

Geospatial Technology: GPS and Remote Sensing

Investigating the principles and applications of GPS and remote sensing (satellite imagery) in modern geography.

• Common Core State Standards
• C3: D2.Geo.3.6-8

About This Topic

GPS and remote sensing are two complementary technologies that transformed how geographers collect and interpret spatial data. GPS determines precise location by triangulating signals from a network of satellites orbiting Earth, providing coordinates accurate to within a few meters for consumer devices and centimeters for professional instruments. Remote sensing captures data about the surface of Earth using sensors aboard satellites and aircraft, recording reflected or emitted electromagnetic energy to produce imagery and spectral data. US 7th graders encounter both technologies daily but rarely examine how they work or what they reveal about environmental change.

In the US curriculum, remote sensing connects physical geography to current events. Students examine how satellite imagery documents retreating glaciers in Alaska, deforestation patterns in tropical regions, urban heat islands in Phoenix, and damage assessments after hurricanes in the Gulf Coast. These applications make abstract geospatial concepts tangible and give students tools for evaluating environmental claims with evidence.

The ethical dimensions of GPS tracking make this topic unusually rich for structured discussion. Parental monitoring apps, employee location tracking, law enforcement surveillance, and fitness data collection all raise questions about privacy, consent, and power that 7th graders have strong opinions about. Active learning structures including debate and case study formats help students move beyond recognizing that GPS is useful to analyzing the genuine tradeoffs constant location data creates.

Key Questions

1. How has satellite imagery changed our understanding of Earth's surface?
2. What are the ethical implications of constant location tracking via GPS?
3. Evaluate the impact of remote sensing on disaster response and environmental monitoring.

Learning Objectives

• Analyze how GPS triangulation works by comparing signal reception from multiple satellites.
• Evaluate the ethical implications of location tracking data in at least two different scenarios, such as parental monitoring or law enforcement.
• Compare the types of data collected by different remote sensing instruments, such as optical vs. radar imagery.
• Explain how remote sensing imagery can be used to monitor environmental changes, citing specific examples like deforestation or glacier melt.
• Synthesize information from GPS data and remote sensing imagery to propose a solution for a local environmental issue.

Before You Start

Map Skills and Coordinate Systems

Why: Students need a foundational understanding of how locations are represented on maps and the concept of coordinates to grasp GPS functionality.

Introduction to Earth's Physical Systems

Why: Understanding basic concepts of landforms, climate, and environmental processes provides context for interpreting remote sensing data related to Earth's surface.

Key Vocabulary

Global Positioning System (GPS)	A satellite-based navigation system that provides precise location, velocity, and time information anywhere on or near Earth.
Remote Sensing	The acquisition of information about an object or phenomenon without making physical contact, typically from aircraft or satellites.
Satellite Imagery	Digital images of Earth's surface or atmosphere taken from satellites, used for various analytical purposes.
Geospatial Data	Information that describes both the location and the characteristics of geographic features on Earth's surface.
Triangulation	A method used by GPS to determine a location by measuring the distance from at least three known points (satellites).

Watch Out for These Misconceptions

Common Misconception

GPS and GIS are the same thing.

What to Teach Instead

GPS is a positioning system that determines where something is located on the surface of Earth. GIS is an analytical platform that processes and visualizes spatial data from many sources, including GPS. GPS provides one type of input to GIS, but GIS also uses census data, satellite imagery, survey results, and many other data types.

Common Misconception

Satellite images show what the surface of Earth looks like right now.

What to Teach Instead

Consumer satellite imagery including the base layer in Google Earth is typically several months to several years old. Real-time commercial satellite feeds exist but are expensive and reserved for specific applications. Remote sensing analysts always check the acquisition date before drawing conclusions from imagery.

Common Misconception

Remote sensing is only useful for studying distant or exotic locations.

What to Teach Instead

Remote sensing is used to monitor farms, suburban watersheds, city heat islands, local wetlands, and neighborhood tree canopy. The technology is just as relevant at local scales as at global ones, and some of the most actionable environmental data comes from regional remote sensing studies close to home.

Active Learning Ideas

Think-Pair-Share: Before and After Satellite Images

Students examine two satellite images of the same location taken years apart using NASA Worldview, USGS EarthExplorer, or Google Timelapse. Pairs identify visible changes, propose causes, and discuss what the change suggests about human activity or natural processes before sharing interpretations with the class.

25 min·Pairs

Gallery Walk: GPS Ethics Scenarios

Stations present different real-world GPS tracking scenarios: school bus tracking, employee monitoring software, electronic ankle bracelets, fitness app location data, and targeted advertising based on frequent locations. Small groups analyze the privacy-safety tradeoff at each station, leaving sticky notes with their assessment, then review and respond to other groups' notes.

30 min·Small Groups

Case Study Analysis: Disaster Response Mapping

Small groups receive satellite imagery from a real natural disaster such as earthquake rubble, hurricane flooding, or a wildfire burn area, along with a list of aid decisions to make: where to land supply helicopters, which roads to prioritize for clearing, which areas need immediate evacuation support. Groups present their decisions and the image evidence that justified each choice.

40 min·Small Groups

Simulation Game: How GPS Triangulation Works

Students act as GPS satellites and receivers using a classroom activity: three students hold strings of measured length from fixed points, and the student at the intersection represents the receiver's calculated position. The class adjusts string lengths to model signal timing error and discusses why four satellites are needed for accurate 3D positioning.

20 min·Whole Class

Real-World Connections

• Urban planners use satellite imagery from companies like Maxar Technologies to monitor land use changes, track urban sprawl, and assess the impact of new infrastructure projects in cities like Denver.
• Emergency management agencies, such as FEMA, utilize GPS data from first responders and satellite imagery to coordinate disaster relief efforts following events like wildfires in California or hurricanes along the Gulf Coast.
• Farmers employ GPS-guided tractors and remote sensing data to optimize crop yields by precisely applying water and fertilizer, a practice common in agricultural regions like the Midwest.

Assessment Ideas

Exit Ticket

Provide students with a scenario: 'A new shopping mall is proposed for a forested area near your town.' Ask them to write two sentences explaining how GPS could be used in this situation and two sentences explaining how satellite imagery could help assess the environmental impact.

Discussion Prompt

Pose the question: 'Is it okay for companies to collect data about where you go all the time?' Facilitate a class discussion, prompting students to consider the benefits of location tracking (e.g., navigation, safety) versus the drawbacks (e.g., privacy, surveillance).

Quick Check

Show students two different types of satellite images of the same area (e.g., one optical, one infrared). Ask them to identify one key difference in what each image reveals and explain why a geographer might choose one over the other for a specific task.

Frequently Asked Questions

What is the difference between GPS and GIS?

GPS (Global Positioning System) is a navigation technology that tells you where something is by measuring signals from satellites. GIS (Geographic Information System) is an analytical tool that processes and layers spatial data to help answer geographic questions. GPS provides location data that GIS can use, but GIS also works with many other data types. They are related but serve different purposes.

How does remote sensing work?

Remote sensing instruments on satellites or aircraft detect electromagnetic energy reflected or emitted from the surface of Earth. Different materials reflect different wavelengths: healthy vegetation reflects strongly in the near-infrared spectrum, for example. By analyzing these spectral signatures, scientists can map land cover, vegetation health, water temperature, soil moisture, and many other surface properties without physically visiting the location.

How has satellite imagery changed disaster response?

Satellite imagery allows emergency managers to assess damage across large areas within hours of a disaster, even when roads are impassable. Teams can identify collapsed structures, measure flood extent, locate displaced populations, and prioritize rescue operations using imagery. This capability has significantly improved the speed and targeting of disaster relief efforts worldwide.

What are active learning activities that help students understand GPS and remote sensing?

Before-and-after satellite image comparisons work well because students make real observations and generate genuine hypotheses. GPS ethics debates engage students who already have strong opinions about location privacy. Disaster response case studies using actual imagery combine geographic analysis with decision-making. These approaches are more effective than explaining the technology abstractly because students interact with real data.