In my project I studied a GRIN tank. It is possible that this tank can be used as a conceptual model of space-time curvature. The tank is made up of a water corn-syrup gradient in which the index of refraction varies in the vertical plane but does not in the horizontal plane. When I shined a beam through the tank, the beam bent toward the higher index of refraction. This is due to Fermat's Principle which describes light as following the quickest path in a given medium. In my study of the GRIN tank, I developed two methods to measure the index at different depths. One method involves measuring a reflection coefficient of the beam; while the other deals with measuring the angle at which it bends over a short distance. The future implications of this study has horizons with conceptually modeling the curvature of light around a gravitational field such as a black hole.