In this lesson students learned about the structures of the eye, and working in pairs dissected a sheep eye. After identifying the optic nerve and trimming off excess muscle and fat from the outside of the eyeball, students cut the eyeballs into a front half and a back half. At the front of the eyeball, they located and observed the iris and the lens. Most students removed the iris in order to better observe the colored part at the front and the muscles visible at the back. Some also cut the lens and observed its layered structure. At the back of the eye, students found the retina and its blind spot, noticing that it matched up with the position of the optic nerve on the back of the eyeball. They also found a surprise difference between sheep eyes and human eyes: there is a beautifully colored membrane, called the tapetum, behind the retina that aids the animal’s night vision.
Students did a great job managing their dissections and observing their specimens!