McCurdy High School Earth Sciences Class: Mapping the World

We’re very excited to be working with McCurdy High School this year. We met Melissa Berryhill at a Forestry and Fire Ecology workshop last summer, and she invited us to work with her classes of Earth Science students. We’ll meet twice per month, once during her class periods to front load the material and then we’ll have an all day field trip to learn how Earth Science is applied in real life.

In September, Ms. Berryhill was teaching her students to read maps. For our classroom session, we discussed trilateration. This is the process of determining location based on distances. For our classroom day, students were given maps of New Mexico and their distance from a city and told to determine their location. They quickly realized that they didn’t have enough information. After using a compass to draw a circle with all possibilities, students were given their distance from another city. With two circles, they narrowed it down to two possible locations. Only after given a third distance could they determine their exact location.

Photo courtesy of

This principle, along with D=RxT, is how the global positioning system (GPS) works. Students used GPS units in teams. Ms. Berryhill taught her classes to geocache to practice this important skill.

Our field day for September took place near Abiquiu. Students were divided into teams and provided with GPS units, navigational compasses, and terrain maps. Each team had the coordinates of a “victim” of a backcountry accident. They had to use the GPS unit to find their victim (a bandana buried in the rocks). This was not always straight forward. Several teams walked right up to a cliff, but had no way to climb it! Fortunately, the terrain map solved this problem, and all groups were able to locate multiple victims.

A “victim” lies under some rocks.

Students also had to use the terrain map to find the nearest LZ- a landing zone for the rescue helicopter. After determining an appropriate LZ, they had to use their compass to find a heading that they could use to evacuate their victim.

Students running to the rescue!

All of the students did really well- by the end of the activity, everybody could use a GPS, a compass, and a terrain map. Mission accomplished!

Special thanks to TWC volunteer Ann Sherman for helping us out with this activity!


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