I. MEASURING TOOL
Our tool is a "sextant". We use the viewfinder (the pipe of paper) to aim the element that we want to measure. Thus, thanks to a weight (here the pencil) the twine shows the angle between the ground and the element. Then, if we know the distance between the building and us, we just need to do some trigonometry to find the height of the aimed element. Finally, we don't forget to add the person's height (from the ground to the eye) to the height previously found for the total height of the element.