Grade Six Science

Do you see the sockets in the picture of the skull above?

Hello Boys and Girls,

How have you been? Have you received any of the results of the NGSA Mock Exam #2? I hope you did very well. Check for any weak areas you may have and work harder at them. Let’s look at a different topic, the Senses. How many senses do you have? Yes, there are five basic human senses. Name them with a friend. Did you name touch, sight, hearing, smell and taste? You know these senses already. The sense organs associated with each sense send information to the brain to help us understand and perceive the world, everything around us. Do you know there is thought to be other human senses in addition to the basic five that were just mentioned? Do you know any of them? Find out.

Look at the pictures below.

First we will look at sight, or perceiving things through the eyes. Sight is a really complex process. First, light reflects off an object to the eye. Use a mirror to observe your own eyes. Look at another person’s eyes.

Now draw a picture of your eye to show

The the eyelids and eyelashes

the white part

the coloured part

the inner black circle

eyes are the sense organs of sight through which we find out many things about our surroundings. How many eyes do persons usually have? Why do we need two eyes? Discuss this with your friend.

Each eye is shaped like a small ping–pong ball. Since the eye itself is shaped like a ball, it is called the eyeball. Only a small part of each eyeball can be seen in front. Most of it is surrounded and protected by a deep, rounded space in the skull bone, called the socket.

Each eye is held in place by six muscles. These muscles move the eyes so that you can look at things all around you.

Let’s look at the parts of the eye more closely.

The skin which is used to cover the eye is called the eyelid – upper and lower. Look at the coloured part. It is called the iris. What colour is the iris of your eye? Your friend’s eye? When we refer to the colour of someone’s eye, we are really referring to the iris. The muscles of the iris control the amount of light entering the eye.

The pupil is a hole or opening in the centre of the iris. It allows light to enter the eye. The size of the pupil can change. The muscles of the iris regulate or control the size of the pupil. In dim light, the pupil gets larger allowing much light to enter, and in bright light it gets smaller, allowing a small amount of light to enter the eye.

The whole front surface of the eyeball is covered by a thin, clear layer. This is the cornea. It protects the front of the eyeball and makes it look shine like glass. Behind the pupil is the lens through which light passes on to the retina. Find the parts discussed in the diagram below.

How do we see?

Light comes into the eye from an object. The lens helps to make the image on the retina. The image is upside down and smaller than the object. When the image is formed on the retina, messages are sent along a nerve (the optic nerve) to the brain. The brain turns the image the ‘right – way up’ and helps us to understand what we are looking at.

Let’s find out how much you know about the eye. Answer the questions which follow.

1. Draw and label the side view of an eye.

2. The eye is the organ associated with ……….

3. Describe how light enters the eye.

4. List two functions of the iris.

5. On which part of the eye is the image of objects formed? 6. How does the brain affect the image seen?

7. How should you care for your eyes? List at least two ways.

Looking back, then, we see that the transparent outer layer of the eye, called the cornea, bends the light that passes through the hole of the pupil. The iris (which is the coloured part of the eye) works like the shutter of a camera, retracting to shut out light or opening wider to let in more light.

The cornea focuses most of the light, then the light passes through the lens, which continues to focus the light,

The lens of the eye then bends the light and focuses it on the retina, which is full of nerve cells.. The information translated from the light is sent as electrical impulses to the brain through the optic nerve.

Until next week, goodbye, Boys and Girls and do care your eyes and other sense organs!