The human eye may be only about the size of a ping-pong ball, but it is an amazingly complex sensory organ that requires all of its components to function properly in order for a person to have optimal vision. Each part of the eye works together with the others to process light rays into electrical impulses, or messages that are transmitted to the brain. The brain interprets this information and allows us to be aware of our surroundings. Our eyes and brain are able to capture and interpret millions of images a day, shaping our view of the world.
Bacteria are one-celled organisms that can only be seen under a microscope. There are thousands of kinds of bacteria, and they are found everywhere – in the air, in the depths of the ocean, in the human body and on human skin. Under favorable conditions, bacteria can multiply rapidly and form colonies (millions of bacterial cells grouped together) that can be observed with the naked eye. In this activity, students will formulate a hypothesis about which area of skin on their bodies may have the most or least amount or kinds of bacteria.