Lenses

There are two types of lenses; convex and concave lenses.

























Concave lenses are thinner at the center and thicker at the edges. They are able to bend light rays away from each other to form a larger image than the object and in same order.


Convex lenses are thicker at the center and thinner at the edges. They are able to bend light rays towards each other so that they meet at a focus. The image formed by a convex lens is inverted and smaller than the object.

How the Eye Works

We are able to see when light from an object enters the eye. It passes through the cornea, then through the pupil at the center of the iris. Light then goes through the lens which bends the light rays towards each other to form an inverted image on the retina. The light rays are changed to electrical impulses which are criiied by the optic nerves to the brain to be interpreted. The brain interprets the image the right way up and we are able to see.

Diagram of the eye

This is a picture of the human's eyes as
seen from a front view when in the head.





















This is a diagram of the crossection of the eye with the inner parts shown.

The eye as a sense organ

The eye is the sense organ of sight. Its parts include:-
the cornea which is a transparent layer at the front of the eyeball.
the sclera, which is the white outer layer of the eye.
the iris is the coloured part of the eye which controls the amount of light entering the eye.
the pupil is found in the center of the iris and is the opening through which light enters the eye.
the lens is found behind the pupil and is responsible for forming the focusing an image on the retina.
the retina is the light sensitive screen which forms the inner layer of the eye and on which the image is focused.
the optic nerves takes images from the retina to the brain.

Graph of Students' height in Grade 5

The data for this graph was collected from students in my Grade 5 class as a Mathematics activity while teaching Measurement.

Survey

Tracy Mills
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