Before you start building your slides, make sure you have everything you will need, including slides, cover slips, droppers or pipets and any chemicals or stains you plan to use.
You will be using two main types of slides, 1) the common flat glass slide, and 2) the depression or well slides. Well slides have a small well, or indentation, in the center to hold a drop of water or liquid substance. They are more expensive and usually used without a cover slip.
Standard slides can be either plastic or glass and are 1 x 3 inches (25 x 75 mm) in size and 1 to 1.2 mm thick.
Wet slides will use a cover slip or cover glass, a very thin square piece of glass (or plastic) that is placed over the sample drop. Without the cover in place, surface tension would cause the droplet to bunch up in a dome. The cover breaks this tension, flattening the sample and allowing very close inspection with minimal focusing. The cover also serves to protect the objective lens from interfering with the sample drop.
There are four common ways to mount a microscope slide as described below:
In a dry mount, the specimen is placed directly on the slide. A cover slip may be used to keep the specimen in place and to help protect the objective lens. Dry mounts are suitable for specimens such as samples of pollen, hair, feathers or plant materials.
In a wet mount, a drop of water is used to suspend the specimen between the slide and cover slip. Place a sample on the slide. Using a pipette, place a drop of water on the specimen. Then place on edge of the cover slip over the sample and carefully lower the cover slip into place using a toothpick or equivalent. This method will help prevent air bubbles from being trapped under the cover slip.
Your objective is to have sufficient water to fill the space between cover slip and slide. If there is too much water, the cover slip will slide around. Take a piece of paper towel and hold it close to one edge of the cover slip. This will draw out some water. If too dry, add a drop of water beside the cover slip. Practice this until you get used to it.
Wet mounts are suitable for studying water-bound organisms such as paramecium or bodily fluids such as saliva, blood and urine.
In a section mount, an extremely thin cross-section of a specimen is used. Using a microtome, cut a thin slice of your selected specimen such as an onion, and carefully set it on your slide. Then follow the instructions for a dry or wet mount. A stain can often be applied directly to the specimen before covering with a cover slip.
Section mounts are suitable for useful for a wide variety of samples such as fruit, vegetables and other solids that can be cut into small slices.
A smear is made by carefully smearing a thin layer of the specimen across a slide and then applying a cover slip. Typically, a smear should be allowed to air dry before applying a stain.
Stains are used to help identify different types of cells using light microscopes. They give the image more contrast and allow cells to be classified according to their shape (morphology). By using a variety of different stains, you can selectively stain different areas such as a cell wall, nucleus, or the entire cell. Stains can also help differentiate between living or dead cells.
Stains tend to be grouped as neutral, acidic or basic, depending upon their chemical makeup and will attract or repel different organisms accordingly. For example, scientists and health professionals use Methylene Blue, a slightly alkaline stain, to reveal the presence of deoxyribonucleic acid, more commonly known as DNA.
Iodine is one of the more commonly available stains and is used to identify starch in a variety of samples. It will stain carbohydrates in plants and animal specimens brown or blue-black. Glycogen will show as red.
Methylene Blue is an alkaline stain useful in identifying acidic cell nuclei and DNA in animal, bacteria or blood samples. It’s also useful in aquariums to prevent the spread of fungal infections in fish. See more details >
Eosin Y is an acidic stain which stains pink for alkaline cells (cytoplasm, for example). It colors red for blood cells, cytoplasm and cell membranes. Eosin's most important medical uses are in blood and bone-marrow testing, including the PAP smear. See more details >
Gram's Stain is one of the most frequently used processes in identifying bacteria – used daily in hospitals. It is a primary test that quickly and cost effectively divides bacteria into one of two types: Gram positive or Gram negative. See more details >
Don't let your microscope gather dust in a corner! Start making your own slides to view at home.
There are two different ways we homeschoolers can mount our samples for microscope slides - wet-mount or dry-mount.
In this article, we are going to look at the advantages and disadvantages of both options along with how to make these slides and a free microscope printable for you to use!
Let's dig in . . .
Like I said, in the homeschool setting, we typically only the dry-mount or the wet-mount method of securing samples on slides for viewing.
But before we go into detail about these two methods, let's chat about how to handle slides. Here are a few essential tips:
Whew, with that out of the way, let's chat about making some slides!
A dry-mount slide is when the sample is simply placed on a slide . . . simple, huh?
You can use a coverslip or another slide to flatten the sample or hold it in place if necessary.
You should use this type of slide when viewing samples such as pollen, feather, or hair.
How to make a dry-mount slide
When making your own dry-mount slides, you will want to follow these directions:
Once you view your slide, wipe it off thoroughly with 70% ethanol and a clean lens cloth to reuse the slide for another sample.
A wet-mount slide is when the sample is placed on the slide with a drop of water and covered with a coverslip, which holds it in place through surface tension.
You should use this type of slide when viewing living samples such as saliva, blood, and other cells.
How to make a wet-mount slide
When making your own wet-mount slides, you will want to follow these directions:
Once you view your slide, you can gently separate the coverslip and slide. Then, clean both thoroughly with 70% ethanol and dry with a lens cloth to reuse the slide for another sample.
Wrapping it up (& a FREE Printable)
As you view the slides you have made, have your students describe what they are seeing. Then, take the time to point out any of the interesting features you want them to notice.
After that, have the students make a notebooking sheet to record the experience. Here's a free printable you can use:
I hope you enjoy looking at the microscopic world as you study science!