Hatchet Planimeters

Our school was doing 3 day trip to Yosemite with the theme of "Restore Hetch Hetchy." Each discipline had to come up with a lesson that related to this theme and I decided to try to use a relatively unknown tool to estimate the volume of water stored by the O’Shaughnessy Dam: a planimeter. There are 3 types of planimeters that I researched: Linear, Polar, and Hatchet. I thought that a hatchet planimeter would be the easiest because as long as you could find a dead branch, a patch of dirt, and the map with the feature that you were trying to calculate the area of, then you were set. I wanted to try to utilize my 3D printer to have a more precise way of measuring area. I ended up giving my Algebra 1, Geometry, Algebra 2, Precalculus, and AP Calculus classes a brief overview of Green's theorem and an informal proof of the theorem with the help of Professor Foote's website: http://persweb.wabash.edu/facstaff/footer/Planimeter/HowPlanimetersWork.htm
and this other website I found: http://u