Disposable Camera Microscopes Page 1

Standards

Lenses & Optics

Safety

Materials

Activity

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National Science Education Standards
Content Standard: 5-8
Science and Technology

CONTENT STANDARD E:

As a result of activities in grades 5-8, all students should develop

• Abilities of technological design

• Understandings about science and technology

DEVELOPING STUDENT ABILITIES AND UNDERSTANDING

Students in grades 5-8 can begin to differentiate between science and technology, although the distinction is not easy to make early in this level. One basis for understanding the similarities, differences, and relationships between science and technology should be experiences with design and problem solving in which students can further develop some of the abilities introduced in grades K-4. The understanding of technology can be developed by tasks in which students have to design something and also by studying technological products and systems.

Texas Essential Knowledge and Skills (Science)
§112.22. Science, Grade 6.

(4) Scientific processes. The student knows how to use a variety of tools and methods to conduct science inquiry. The student is expected to:

• (A) collect, analyze, and record information using tools including beakers, petri dishes, meter sticks, graduated cylinders, weather instruments, timing devices, hot plates, test tubes, safety goggles, spring scales, magnets, balances, microscopes, telescopes, thermometers, calculators, field equipment, compasses, computers, and computer probes;

Texas Essential Knowledge and Skills (Science)
§112.23. Science, Grade 7.

(4)  Scientific processes. The student knows how to use tools and methods to conduct science inquiry. The student is expected to:

• (A)  collect, analyze, and record information to explain a phenomenon using tools including beakers, petri dishes, meter sticks, graduated cylinders, weather instruments, hot plates, dissecting equipment, test tubes, safety goggles, spring scales, balances, microscopes, telescopes, thermometers, calculators, field equipment, computers, computer probes, timing devices, magnets, and compasses;

Texas Essential Knowledge and Skills (Science)
§112.24. Science, Grade 8.

(4)  Scientific processes. The student uses scientific inquiry methods during field and laboratory investigations. The student is expected to:

• (A)  collect, record, and analyze information using tools including beakers, petri dishes, meter sticks, graduated cylinders, weather instruments, hot plates, dissecting equipment, test tubes, safety goggles, spring scales, balances, microscopes, telescopes, thermometers, calculators, field equipment, computers, computer probes, water test kits, and timing devices;

The Build-your-own Microscope project is probably most appropriately aligned with the grade 8 science process TEKS for designing and testing a problem or model:

Texas Essential Knowledge and Skills (Science)
§112.24. Science, Grade 8.

(5)  Scientific processes. The student knows that relationships exist between science and technology. The student is expected to:

• (A)  identify a design problem and propose a solution;

• (B)  design and test a model to solve the problem; and

• (C)  evaluate the model and make recommendations for improving the model.

A few Definitions:

The focal point of a lens is the point where light rays converge after passing through the lens. The distance from the focal point to the lens is defined as the focal length of the lens.

A real image is one formed by rays of light, while a virtual image is one that only appears to be formed by such rays.¹ Real images are capable of being projected onto a surface, but virtual ones are not - in other words, if you line up a candle, a magnifying glass, and a white card, when properly arranged an upside-down image of the candle is displayed on the card. This is a real image.

When working with disposable cameras, there are two very important safety considerations. First, these cameras usually contain CAPACITORS which store electrical charges used in setting off the flash. These capacitors can (and usually do) contain voltages which are quite high, and can remain charged after the camera is used. A capacitor can give a sharp, painful, and potentially dangerous shock if it (or the circuit it is part of) is touched by a person, and care should be used when opening the camera. It is recommended that only the teacher should pry apart the camera, while using a tool (such as a flat-bladed screwdriver) with an insulated handle. After removing the camera's lens, dispose of the camera's remains in sealed garbage, where children will not touch it. Secondly, whenever you are using a tool such as a screwdriver to pry open the camera, be careful and protect your eyes with goggles. Also, only the teacher should use the drill or any other sharp object.

• A few used disposable cameras (free for the asking from many stores where developing and printing is done)

• A flat-bladed screwdriver or similar tool for prying open the camera.

• White glue (e.g.: "Elmers" ™) - perhaps a toothpick for positioning the glue.

• An empty plastic water bottle, or a variety of other "mounts". Use your imagination. What might you mount your magnifying lens in?

• A drill with a large diameter drill bit.

• eye protection and other safety equipment as needed (such as a board for supporting the bottle cap when drilling into it).

Stores that develop film will often give you some of these for free - say thank you, though, since the stores can potentially recycle them for about $1 each.

An open disposable camera. The capacitor is soldered into the camera.

One variation is to cut off and use the screw-top of the bottle to provide an adjustable mount for the cap. This may be more appropriate for some lenses than others, since effective use of an adjustable mount of this kind depends on the focal length of the particular lens, and works better with some bottle caps than others. If the lens' focal length is long enough*, then this kind of mount allows a viewer to place an object (such as an insect) under the cap, and by rotating the cap in its screw-mount, move the lens up and down, bringing various parts of the object in focus.

*How long would the focal length be? Think for a moment...it should correspond to the distance between the lens and the film in the camera...why?

Step 1: Remove any cardboard or external packaging. Note that the lens we seek is the one through which the photographic image is made (don't use the viewfinder lens).

Step 2: pry off the front of the camera (a flat-blade screwdriver is a good tool for this). Avoid the area around the flash. When you get the front off, note that there is a battery inside...another, more dangerous electrical storage device is the capacitor (which is charged by the battery and holds a much higher voltage).

Step 3: Carefully pry off the plastic ring that holds the lens in place. Once you have the lens, dispose of the rest of the camera in the garbage (where children cannot get to it).

Step 4: Mount your lens in an appropriate holder...in this case we have drilled a large hole in a bottle cap, and have used a bit of white glue to make a "loupe" (a form of simple microscope). It is great for looking at insects.
       

Once the lens is mounted in the cap, and the glue is dry, the loupe lens forms a virtual image.

http://www.exploratorium.edu/snacks/giant_lens/index.html

The Exploratorium's "Giant Lens" activity. The Exploratorium is one of the world's leading locations in illustrating fundamental science concepts with simple activities.

http://www.sciencenetlinks.com/lessons.cfm?DocID=378

Science Netlink's "Pond 2: Life in a pond of water" activity (grades 3 - 5). Science Netlinks is produced by American Association for the Advancement of Science, and is part of the MarcoPolo group of teacher resources.

http://www.microscopy-uk.org.uk/primer/index.htm

Microscopy-UK's Microscopy Primer - a one-stop shop for explaining how microscopes work.