A basic introductory lesson for your fifth graders can be an anatomy-based activity. Project a labeled eye diagram on a projector screen in your classroom and briefly explain the parts of the eye to your class. Pass out the eye diagram with no parts labeled and see how well your class can remember the parts as they use a word bank to label their individual diagrams. Consider including parts such as the iris, pupil, vitreous humor, lens, optic nerve and cornea.
Another way to engage the attention of your class is to compare the human eye to the eyes of other species, such as insects. Besides examining the anatomical differences between the eyes of humans and other animals, try to give your class insight into how various animals see the world. For example, insects see the world in ultraviolet light, which allows them to seek out pollen and nectar.
Although fifth-grade students are unlikely to have had laser eye surgery at their age, some may have parents who have undergone the procedure. Even if students are unfamiliar with the surgery, this can be an intriguing topic because of the novel nature of using lasers to reshape the eye. Using a handout to provide easy-to-understand information and guide class discussion.
Another interesting lesson on the eye for fifth graders involves explaining stereo vision. Stereo vision refers to the way humans can see three dimensions due to the location of our eyes. Explain the advantages of this setup, such as depth-perception, and have your students brainstorm situations in which a lack of stereovision would inhibit everyday life.
Investigating optical illusions is a fun lesson that explores the quirks of the eye and stereo vision. The National Institute of Environmental Health Sciences has organized a number of optical illusions to explore. These optical illusions include parallel lines that appear crooked and static circles that appear to move when you shift your focus.