Students can collect their own items to look at and/or teachers can provide objects.
Ideas of things to look at:
Your own skin, fingerprint, hair, nails.
Man-made items such as fabrics with different weave densities, paper with different texture and colour printing (to see the individual coloured dots).
Natural organic items such as fur, wood, feathers and seeds.
Natural inorganic items such as crystals (including salt) and rocks with different mineral colours in them.
Living samples such as pond water or soil containing small animals.
A microscope can be set up in the classroom, or outside if power can be run outside.
If any collected specimens are animals, students should ask an adult to help them put it in a collecting with some dirt and/or leaves, and return it to the same place after class.
A sequential magnification of specimens, from looking closely with the naked eye, to looking with a magnifier, to looking with a microscope, give a good sense of what is being looked at. What can you see with the magnifiers that you were not able to see with your naked eye? What were you able to see with the microscope that you were not able to see with the magnifier? It also creates a wonderful zoom into the details upon details in objects - there is so much going on that we don't usually see, and understanding the structure in more detail can help us understand function.
Proper use of magnifiers
Great for younger students.
Hold the magnifier 5-8cm from one eye, and look through it. Hold a finger on the other side of the magnifier, 5-10cm away from it. Then move the finger slightly until it is large and clear (in focus). Students should be able to easily see their fingerprint. The key point is not to have either your eye, or the object being viewed, touching the magnifier.
Use the same method to look at specimens. Sometimes, instead of moving the specimen closer to the lens, it will be easier to move your eye and magnifer (keeping them apart) towards the specimen.
(See the Open Door Website at http://www.saburchill.com/lab/observations/observe01.html). The curved glass makes things look bigger. Ask students to make a drawing of their living thing, showing the details that they can now see with the magnifier that they could not see with the naked eye.
Proper use of stereo (dissecting) microscopes
Good for primaries and up.
Place an object on the stage, and while watching from the side, turn the focus knob to bring the lens as close to the object as possible without touching it. While looking through the ocular lenses on top, slowly focus up until the object is in focus. The stereo microscope magnifies 20 to 40 times, so bridges the gap between the visible and microscopic.
Proper use of transmission (compound) microscopes
Best for intermediate and older students.
The transmission microscope magnifies 40 to 400 times, and can be used to look at small details invisible to the naked eye. The light comes from underneath so the sample must be thin enough for light to pass through, and for the lens to move over. The sample can be mounted on a slide, or simply placed under the lens if it is flat enough to fit. To prepare a slide, place the specimen on the slide and add a small drop of water if necessary. If needed, arrange the specimen with a toothpick. Lay over the cover slip, by lowering from one side. First view the slide at the lowest power (40X), by starting with the objective lens at its lowest point and moving it upwards with the coarse focus knob, until the sample is in focus. Then the higher power lenses can be used in sequence, adjusting the focus using only the fine focus knob.
More detail on microscope use and specimen ideas:
http://www.saburchill.com/lab/observations/observe04.html
Levine, Shar and Johnstone, Leslie. 1996. The microscope book. Sterling Publishing Company
Further magnification in scanning electron microscope images
Show images of familiar living things magnified even further:
scanning electron microscope images at:
http://www.denniskunkel.com
Scharf, David. 1977. Magnifications. Publisher Schocken
Breger, Dee. 1995. Journeys in Microspace. Columbia University Press
or a google image search of "scanning electron microscope images"
