Playground Profiling: Topographic Profile Mapping

Overview

This lesson was modeled after some of the routine activities undertaken by the geologists on the Kuril Island Expedition.

Complete the following activities:

• Day 1 To measure a simple topographic profile with a level instrument or hand level and stadium rod.

• Day 2 To use the measurements from Day 1 (and/or actual measurements from the Kuril Islands) to create a horizontal topographic profile.

Objective

Students will continue to become familiar with topography, while practicing skills in data collection, mapping, and graphing.

Preparation

Notes: Students will need to be familiar with the concept of topography at a minimum. While it is helpful if they know how to use similar triangles for this activity, it is not essential. If students have not mastered coordinate graphing by hand or with graphing software, that portion of the lesson will need to be increased in length to incorporate this instruction.

Background for Teacher: The surveyor's tripod level uses similar triangles and three measurements to determine both the height and distance to the stadia rod. The center measurement gives the height and the upper and lower measurements, which should be evenly distant from the center measurement, are used to calculate the distance to the rod. Due to the stability of the instrument and its precision, measurements taken this way are more accurate over long distances. The height readings need to be corrected for the eyepiece height by subtraction. The difference between the upper and lower readings is multiplied by 100 to calculate the distance in meters.

For example, if the eyepiece of the instrument is 1.46 m and the readings are 1.119 m (upper), 1.1 m (center) and 0.982 m (lower), then the height at the reading point is 1.46 – 1.1 = -0.36, or 0.36 m LOWER than the tripod, and the distance of the reading point is (1.119 – 0.982) * 100 = 13.7 m away from the tripod.

In this way, a sequence of elevation and distance measurements, relative to the location of the tripod can be measured and then plotted to give a horizontal topography. If a surveyor's tripod level is not available, then there are two other options – a hand level, which gives the same information as tripod level, but is less accurate due to the need to hold the level steady while taking the measurement, or a handmade level, such as a clinometer constructed from a protractor, straw and a weighted string, that can measure the height. If a handmade level is used, then the distance to the rod, must be made manually with a tape measure.

Procedure

Outline of Tasks:

Day One:

1. Set up simple varied topography profile on the school grounds using tables, playground equipment or natural features. Try to make the profile at least 25 meters long, with only 1-2 meters of elevation change so that all of the measurements can be taken from one location.

2. Divide the students into groups of 3-4 and then divide the groups into two groups – one that will take measurements with tripod level and one with hand level.

3. Illustrate the process on the white board showing how height measurements are taken at various distances with the levels and then used to determine the elevation of the ground.

4. Set up data tables in the Student Journals.

5. Make measurements – having students rotate through the stations of reading measurements, holding rod, and recording readings.

Day Two:

1. Do an example set of measurements (perhaps a portion of an actual profile from Kuril Islands) to demonstrate how the calculations are done.

2. Use the measurements from Day One to calculate elevations for the "playground profile".

3. Actual measurements from Kuril Islands, such as those for Lovtsova on Kunashir, could be used in place of playground measurements. Or these measurements could be used as an assessment, extension or follow-up activity.

4. Once calculations are complete, graphs can be made.

5. Differentiation for ability levels: grids with pre-determined scales and intervals could be given to younger students, while older students could use spreadsheet software to do both calculations and graphing.

6. Use the graphs to identify "features" in the profile of the playground. Could use graphs of actual data to identify features as an assessment tool.

Credits

Misty Nikula, Whatcom Day Academy