Teaching Notes

Example Output

Screen capture of Google Earth map showing the locations of litter and trashcans in a park or school ground. User-generated data will differ.

Grade Level

This chapter is designed to be used as a professional development activity for educators. It can also be used with students. It is written primarily for students in grades 9-12. However, it can also be used by students in grades 4-8 who wish to venture into the world of technology. Undergraduate students who are new to the use of Global Positioning System (GPS) receivers will also benefit from this chapter.

Learning Goals

After completing this chapter, students will be able to:


Although the exercise of mapping the location of trash in a park or on a school campus seems to be a fairly straightforward one, it helps users to learn the basic skills of data collection, management, integration, analysis, and visualization. These basic skills are important for users to have mastered prior to moving on to more complex geospatial activities.

The same skill-set illustrated in this chapter can be used to answer other geospatially-based decision-making activities such as:

Background Information

Information about Litter:

Information about Google Earth:

Instructional Strategies

Imagine working through the scenario discussed in the Case Study with local citizens, students or park volunteers. On the surface the question seems simple: where are the optimum places to locate trash cans and recycle bins? Where are they most needed and yet still easily accessible for maintaining on a regular basis? How many are needed? How large? How would you coach a team to come up with a concise problem statement and parameters that the whole team agrees upon? How would you approach the data collection task?

If necessary, review the latitude and longitude coordinate system with students. Although coordinates can be recorded in several different formats with a GPS, decimal degrees is commonly used for mapping applications. The format settings on the eTrex Legend are found at Main Menu > Setup > Units > Position Format. Select hddd.ddddd for decimal degrees. Prepare the units in advance of the practice session.

Participants should be engaged and motivated to take ownership of this activity. Consider introducing the activity by showing photos of trash around a school or a park. Ask a series of questions aimed at identifying and defining the issue:

Before collecting data, discuss with the group how they will quantify the litter. If they find 4 gum wrappers on the ground, ask if they should mark four waypoints, or will that be considered one point of litter? Ask participants if the litter needs to be a certain distance apart to be considered two waypoints. For example, if there are 2 hamburger wrappers 30cm apart, will that be one point or two? Have the team come to a consensus on measurements before collecting data.

Prior to going outdoors to collect data, users should be familiar with the GPS model being used and how to mark waypoints. If available, use a document camera to display the different pages of the GPS unit and steps for marking a waypoint. Once users are familiar with the functions of the unit, have them work in small groups to practice working with the GPS in a controlled situation, such as on a ball field or outdoor playground.

The number of GPS units will most likely be the limiting factor. Group users according to the number of GPS units available for the activity, ideally have one GPS for every 3-4 users. If fewer GPS units are available for use, consider setting up a stations-based lab activity, so that all participants have something to do during the activity. Loaner GPS units are available from a variety of sources, see Going Further for ideas.

In the small teams of 3-4 participants, one person can mark the waypoints with the GPS, a second is responsible for recording the data (the coordinates) on a paper datasheet along with a description, and, third group member can serve as the litter "scout". If digital cameras are available, one group member can photograph the litter to add an illustration to the placemark. Have students rotate roles during the activity.

Learning Contexts

This lesson has users collecting data and visualizing locations of litter around a school, however the process of marking waypoints and importing them into Google Earth could be used in a variety of contexts. The most basic skills this lesson focuses on are problem identification, problem solving, geospatial analysis and map presentation skills. This lesson provides opportunities for users to develop and master these hands-on skills. Examples of other specific contexts in which the processes described in the lesson could be used are:

National Science Standards

Grades 8-12

National Geography Standards

The following National Geography Standards are addressed in this chapter:

The World in Spatial Terms

1. How to Use Maps and Other Geographic Representations, Tools, and Technologies to Acquire, Process, and Report Information From a Spatial Perspective

3. How to Analyze the Spatial Organization of People, Places, and Environments on Earth's Surface

Student Evaluation

After collecting the data using a GPS, importing and analyzing the data in Google Earth, student groups can prepare and present their possible solutions and conclusions. Consider using a well structured rubric to communicate expectations in a clear and concise format to help guide student work on the activity. Here is a list of possible assessments for a rubric:

Time Required

At least three 45-minute periods will be needed to fully complete the activity outlined in this chapter.

Other Resources

Data Recording Sheet (Acrobat (PDF) 36kB Sep28 10) (in PDF) for use with this Exercise

Litter Retriever Practice KMZ file (KMZ File 2kB Aug18 10)

How to use a GPS Unit

Google Earth Tutorials

Google Earth User Guide

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