Measure the height of a rocket using a protractor and some simple mathematics! Make measurements through triangulation with the same method for measuring the length of large or distant objects used by Galileo and Newton. In triangulation, an angle-measuring instrument measures the angle between an object and a horizontal location. If the distance from the instrument to the horizontal location is known, then the distance between the object and the fixed location can be calculated using the laws of geometry that govern triangles. In this activity, students construct their own angle-measuring instrument. A scale rocket is attached to the wall near the ceiling, and the students use their angle-measuring device to determine the rocket’s height above the floor.