In Investigation One, students explored the sense of hearing. They began to understand the contribution that hearing offers to the way we perceive our environment. In Investigation Two, students will consider the sense of sight. Like our sense of hearing, our sense of sight is crucial to making decisions based on our perceptions of the world around us.

We see an object because light is reflected off the object. The reflected light then enters the eye and passes through the cornea, an outer layer of the eye. The light then travels through a fluid called the aqueous humor. Past the aqueous humor, light enters and passes through the pupil, a hole in the center of the iris, which dilates (becomes larger) or constricts (becomes smaller) to control the amount of light entering the eye. For example, when exposed to bright light the pupil becomes smaller so that too much light does not enter the eye.

After passing the iris and the pupil, light passes through the lens. The muscles around the lens allow it to change shape to focus the light onto the retina, a layer of tissue responsible for sensing light. Before reaching the retina, however, light must pass through a second fluid referred to as the vitreous humor.

At this point, light has entered the eye by passing through the cornea, aqueous humor, pupil, lens, and vitreous humor. Light is focused on the retina, which contains cells that convert the light into electrical impulses. These impulses pass through the optic nerve to the brain, where the information is processed so that we may respond to it appropriately.

In Investigation Two, students will utilize their sense of sight to identify properties of objects. In addition, students will use a hand lens to add clarity and magnification to the images of the objects they view.