Two misconceptions about the mechanism of image formation in the human eye are common among students and even in textbooks and other teaching materials. The first attributes all refraction to the eye lens; the second treats the eye as a pinhole camera. To reduce these persistent conceptions of students, a series of simple experiments is presented using a water-filled fishbowl as a model of the eye. The model is used to demonstrate the propagation of light through the eye and the image formation on the retina in normal vision, nearsightedness, and farsightedness. The model also allows visualization of the corrections of malfunctions of the eye.