Introduction to Field Mapping with a Compass and Pace

Richard Tomlinson Math Teacher Peoples Academy in Morrisville, Vermont

Introduction: This lesson uses field mapping as an application of basic geometry and algebra.

Objectives: The students will:

( 1) learn to use a compass and calibrate their own pace,

(2) learn to take field measurements of a pre-set course with a compass and pace (in small groups),

(3) learn to convert field measurements into a map, using angles and vectors,

(4) learn to make a composite class map by adjusting the different scales and orientations of maps made by each small group, and

(5) learn the value of seeing the map view of a large ground object whose shape is unclear from the ground.

Geographic Theme: Location

Geography Standards: Number 1, how to use maps and other geographic representations, tools, and technologies to acquire, process, and report information from a spatial perspective.

Time: 5-6 class periods

Materials:

(1) One hand compass for every two students

(2) 100 foot measuring tape

(3) 6 wooden stakes 3 or 4 feet tall (for reference points)

(4) 15 metal pins or wooden stakes (for stations)

(5) Surveyor's ribbon

(6) Permanent marker

(7) Rulers and protractors

(8) Unlined paper and pencils

Procedure:

Pre-class preparation

( 1) Prepare an overhead showing a hand compass with all the parts clearly labeled.

(2) Pre-measure a soccer field from goal line to goal line and record.

(3) Establish a baseline running parallel to the long axis of the object. Pre-set the 6 reference points at intervals along the baseline (one for each group) with stakes and flagging. Layout the 15 stations with metal pins or stakes and flagging, and number them as in the pattern shown below. (You can also design a different object or animal shape to use rather than the rocket shape, as long as it is entirely made of straight line segments between points).

Classroom Introduction

(1) Explain and demonstrate compass use. Be sure to cover the concepts of true north, magnetic north, bearings, azimuths, line of sight. Point out the various parts of the compass, and describe how it works.

(2) Define a pace and how it is determined.

(3) Provide an overview of the activities to follow. Discuss the need when locating objects of starting from a fixed point or line of reference. Emphasize the importance of accurate and complete record-keeping, including sketches to support the notes taken.

Activity 1: Establish length of step

(I) Take class to the soccer field.

(2) Have students start at one end of the field and walk to the other end at a normal walking speed. As they walk, they count the number of steps they take to reach the other end and record it in their notes. Repeat at least one more time.

(3) Have students calculate their average length of step.

Activity 2: Field work collecting data using a compass and pace

(I) Do a practice session with compasses, having each student ~e a sighting of 3 or 4 distant objects at various azimuths from a pre-selected location. Take the time to make sure all the students have a opportunity to use the compass and obtain an accurate reading.

(2) Go to the pre-set baseline and reference points. Assign each group their baseline reference point and the stations they will measure.

(3) Have students take compass readings from their reference point to all of their assigned stations. Using their calibrated pace, have students measure the distances from the baseline reference point to the first station, and between all their assigned stations.

Activity 3: Mapping the survey

(1) Students will construct a map using their field notes on a sheet of 8 1/2 x 11 unlined paper.

(2) Students must decide on an orientation and scale that will allow them to map their reference point and stations on the one sheet

(3) Put together the individual maps to form a composite map of the entire area surveyed. The shape of the object should become clear, showing that the map view of the object is easier to understand than the view from the ground.