What can you do with a 6-inch piece of string, some tape, a paperclip, a drinking straw, a protractor, and a tape measure? If you’re an 8th grade Geometry student at St. James Lutheran School, you could measure the height of our church’s bell tower!
In order to study trigonometric ratios in real-world settings, the Geometry students set out to measure something that would be too tall to otherwise be measured. The student sketch below shows how this was accomplished. One student was the “observer” while the other was the “measurer.”
The string, paperclip, drinking straw, and protractor were used to make a “clinometer,” or, a device that measures an incline or angle of elevation. The clinometer was used by the observer, who looked through the straw until the top of the steeple was in sight. Once she had the steeple in view, the measurer recorded the obtuse angle shown by the string. The sketch shows the need to subtract 90° so that the angle of elevation could be found.
The tape measure was used to find the distance from the base of the church to the observer’s feet, and also the height up to the observer’s eyes. Once all of these calculations were found, the students used a trigonometric equation and some compensation for the student’s height to come up with a very close estimate to the actual height, which was found in the church’s original blueprints: 126 ft. 7 in
