This article is about the students' investigation about the relationship between the diameter of the view tubes (x) of constant lengths and the viewable vertical distance (y) on the wall while keeping the perpendicular distance from the eyeball to the wall constant. The students collected data and used and represented it in tabular and graphical form and used TI-84 to analyze the data. They also used "Geometer's Sketchpad" to model the investigation. Here, the author documents the results of this investigation. (Contains 7 figures and 1 table.)