Carol Bible Carter Elementary
5740 S. Michigan
Chicago IL 60637
(312) 535-0860


Students in grades 5-8 will discover, through exploration and observation, what
lenses are and what lenses can do.

Materials Needed:

concave lenses solid glass or plastic cylinder
convex lenses paper
Florence glass black marker
plain glass overhead projector with arm lowered
Fresnel lens light box with an arrow on a screen
baggie filled with water lens holders
spray bottle with water index card with "AMMONIUM DIOXIDE" written
meter sticks large lens with long focal length


Opening activities

1. Hand out baggies filled with a convex lens, a concave lens and a plain piece
of glass. Students explore and discuss what they observe about these objects.

2. Set up the overhead projector removing or lowering the arm. Explain that
the overhead projector has a lens with a light below it. Turn off the lights
and spray a steady stream of water over and above the lens. Students will
observe that a sort of funnel can be seen with a narrowing in the middle. The
point at which the spray of water narrows represents the focal point (the point
at which the light rays converge).

3. Hold a piece of blank paper over the lens and find the focal point.
Children will be able to observe that the light will be smallest and most
intense at that point. Then take a black marker and darken the center of the
paper. Hold the paper over the lens again at the focal point. Students will
observe the paper begin to smoke.

4. Show students the light box with the arrow on it. Observe the direction of
the arrow. Turn off the lights and project the image of the arrow on the wall.
Students will observe that the image is upside down.

Stations-Students will be divided into cooperative groups of four. Each group
will receive an activity sheet with activities to be performed and questions to
be answered at each station.

Station #1 - Display convex lenses with various focal lengths. Students will
focus the overhead light onto a paper and notice the distance between the lens
and the brightest image (this is called the focal length). They will do this
for all of the lenses, make observations about the focal length of these lenses
and record any other observations.

Station #2 - Students will find an object in the room and describe the image
that they see when they look at it through a Florence glass and then a baggie
filled with water. Students will determine whether the Florence glass and the
baggie are examples of lenses.

Station #3 - Attach two convex lenses, one with a relatively short focal length
and the other a long focal length, to a meter stick using lens holders. Students
will look through one lens and then both lenses. Then they will focus on an
object far away by moving the lenses back and forth on the meter stick.
Students will determine what happens to the image and what this device could be
used for. (Telescope)

Station #4 - Attach two convex lenses, both with short focal lengths of about 5
cm., to a meter stick using the lens holders. Students will move the lenses
back and forth and focus on a written page from a newspaper or the like.
Students will determine what happens to the image and what this device could be
used for. (Microscope)

Station #5 - Display the Fresnel lens. Students will determine if it is a lens
and if so, how it is the same or different from the other lenses.

Station #6 - Mystery Lab! Students will explain what is happening when they
look at the words AMMONIUM DIOXIDE through a solid glass cylinder.

Performance Assessment:

Activity sheets from each group will be collected and assessed.

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