Half the fun of a compound microscope lies in the slide preparation. This is particularly true with younger children where slide preparation and viewing provides a wonderful opportunity for cross-generational bonding. Moreover, slide preparation is engaging without being overly taxing - a good combination for younger children. For high school students and hobbyists, these basic processes can be applied to any number of different experiments - limited only by your imagination!
WARNING: Adult supervision required when using a microtome, sharp knife, razor blades and stains.
In the late 17th century an Englishman, Robert Hooke, discovered the honeycomb structure or ‘Cells” of a cork when viewing them under his microscope. It was Hooke who coined the term ‘cells’. You can easily recreate Hooke’s experience by following these instructions:
Using great care, cut as thin a slice of cork as possible from the end of the cork. Using the pipette, place one drop of water on the slide. After making sure that the water drop is larger than the slice of cork, use the tweezers to place the slice of cork on the water. Hold the cover slip at an angle to the slide so that one edge of it touches the water drop. Carefully lower the cover slip and ensure no air bubbles are trapped beneath it. The water will seal the cover slip but use the corner of a paper towel to gently absorb any excess water. If you want to retain the slide longer, smear a little petroleum around the cover slip with a toothpick. This will keep it from drying out. Then mount the slide on your microscope and view it using the lowest objective lens, first.
A kid’s favorite! There is nothing like engaging a child by viewing their own body tissue and a cheek cell is a good way to start. Cheek cells are called Squamous Epithelium cells and they are also a good first use of a microscope stain, in this case Methylene Blue.
Scrape the inside of your cheek with the Q-tip and wipe it on to the center of the slide. Hold the coverslip or another slide with one end flush on the slide and gently wipe the edge of the coverslip over the scrapings. This is called a smear and it makes a specimen layer thin enough to view clearly. Leave the cells to dry. When dry, add a drop of Methylene Blue stain. This helps add contrast to the nuclei of animal cells, making them easier to view. Lower the cover slip, mount on your microscope and view starting with the lowest power objective.
This is another good experiment that kids relate well to - and the raw material is in the refrigerator!
Peel the onion and cut a small section from the inside layers of the onion. Use a pair of tweezers to peel away the transparent membrane that you will find on the inside layers. Create a wet mount and add a drop of Eosin Y stain. Eosin Y helps highlight vegetable proteins. Mount on your microscope and view starting with the lowest power objective lens.