The senses of sight and sound are probably the most important senses. Can you imagine what life would be like if you are deprived of these senses? People who have lost the sense of sight live in a world of perpetual darkness while people who have lost the sense of sound live in a world of total muteness. In other words, they become blind or deaf.

The sense of sight makes it possible for people to see. Human beings and animals use their eyes to see. The sense of sound allows people to hear. They do this with the ears. Now, you know why the eyes and the ears are so important. Let's learn about how they work.

How the Eye Works

The simplest way to explain how the eyes work is to think of them as video cameras. When the eyes are open, they are working. Sight begins when beams of light from object or objects go through the cornea to enter the eye. As the light rays each the pupil, the iris adjusts the size of the pupil to accommodate the amount of light. After this, the light rays go into the lens where the image is focused onto the retina through the vitreous humor. The retina is composed of some 150 million light-sensitive cells which are known as rods and cones. Working best in low light levels, rods make out the shapes. Conversely, cones work best in high light levels and they identify color. Via the optic nerve, the information is then sent to the brain. The brain then converts the inverted image right-side up in the visual cortex, letting you know what you are seeing.

• Sense of Sight ��� A clear, simple explanation of how the eye works.
• Anatomy of the Eye ��� Learn about the various parts of the eye.
• Eye Anatomy ��� A diagram of the eye with labeled parts and explanation.
• Diagram of the Eye ��� Fun, interactive way to learn about the eye.
• Animation ��� Check it out to see how images are formed.
• Parts of the Eye ��� Various activities to help kids know more about the eye.
• Your Eyes ��� Interesting and detailed explanation of the eye.
• Optical Illusions ��� Try these exercises to understand optical illusions.
• How the Eyes Work ��� Another explanation to explain how people see.
• Sight ��� View the animation to understand how sight is formed.
• Color Blindness ��� Come here to learn all about color blindness.
• Image Formation ��� An interactive tutorial to show how an image is formed.
• Color Phenomena ��� How do the same colors appear differently?

How the Ear Works

When a sound is made, sound waves travel through the air. The outer ear then captures these vibrations, funneling them into the ear canal. Entering the middle ear, the vibrations cause the eardrum to vibrate too, setting off a whole sequence of vibrations. The vibrations from the eardrum hit the hammer and the anvil before hitting the stirrup. Next, the stirrup transmits the vibrations into the cochlea in the inner ear. There are thousands of cilia (hair-like nerve endings) in the liquid-filled cochlea. As the liquid in the cochlea vibrates, the cilia move and convert these vibrations into messages, passing them through the auditory nerve into the brain. In the brain, the messages are deciphered so you know what you are hearing. Other than hearing, the ears also help people to keep their balance.

• Anatomy & Physiology ��� A great place to learn about parts of the ear and more.
• Ear Anatomy ��� A diagram of the ear with labeled parts.
• Anatomy of the Ear ��� There's a diagram which shows all the various parts of the ear.
• Diagram ��� A simple diagram with all the major parts of the ear.
• Inner Ear Anatomy ��� The pictures show the location of the cochlea, the inner ear fluids, and more.
• Journey through the Ear ��� Simply click on the signs to find out how each part works.
• What is a Wave? ��� A good explanation of sound waves with illustrations.
• Auditory Pathways ��� This diagram shows the major auditory pathways to the brain.
• Hair Cells ��� Here's an image of hair cells in 3D.
• Cochlea Animation ��� Watch this to find out how sound is processed in the cochlea.
• What Did You Say? ��� An animation to demonstrate how the ear works.
• Frequency ��� See the speed of vibrations according to different frequencies.
• How the Ear Works ��� Shows how people hear in relation to cochlea implant.
• Interactive Tool ��� A great way to study more about the human ear.
• Ear & Hearing ��� Click anywhere on the diagram for more information.

Educator Resources

Below are more educator materials which further explain how the eye and ear work.

• Eye Anatomy & Function ��� A great source with lesson plans, experiments, and worksheets.
• Box Eye (PDF) ��� A cool project to explain how the eye works.
• Color Vision ��� Use these lessons to teach students about color perception.
• The Sense of Sight ��� A lesson plan that shows how the eye works.
• Ocular Anatomy (PDF) ��� A teacher's guide to vision.
• Ear Shape ��� Use this lesson plan to teach Grade 3 to 5 students about the ear.
• Sense of Hearing ��� The lesson plan is suitable for students in Grade 1 and 2.
• Sound & Fury ��� PBS presents a series of lesson plans for high school students.
• Worksheet ��� Useful worksheet of the ear.
• The Five Senses ��� A web quest to learn about the five senses, including sight and sound.