microscope experiments pdf

Microscopy for Biology Education. Practical Experiments for Education in Biology

• November 2017
• Publisher: Carl Zeiss AG Jena
• This person is not on ResearchGate, or hasn't claimed this research yet.

• Friedrich Schiller University Jena

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Science Projects > Life Science Projects > Introductory Microscope Experiments  

Introductory Microscope Experiments

You have a microscope—now what?

With these directions, you can get started right away making your own microscope slides!

Make your own prepared slide with mounts of your choice of specimen on glass microscope slides. This is a great microscope activity for junior high to high school age.

Or make simple slides out of household items, a project that works well for elementary age kids and can be used with both compound and stereo microscopes.

In This Project:

How to Make a Slide for a Microscope: Making Your Own Prepared Slides

How to Make a Smear of Cheek Cells

Looking at root and stem sections, how to make simple microscope slides, making simple slides, how to use the microscope, other simple microscope slide ideas, microscope worksheet: recording your microscope observations, how to make a prepared slide for a microscope.

Learn how to make temporary mounts of specimens and view them with your microscope. Below are a few ideas for studying different types of cells found in items that you probably already have around your house. ( Adult supervision required for cutting specimens.)

In the late 1600s, a scientist named Robert Hooke looked through his microscope at a thin slice of cork. He noticed that the dead wood was made up of many tiny compartments, and upon further observation, Hooke named these empty compartments cells.

It was later known that the cells in cork are only empty because the living matter that once occupied them has died and left behind tiny pockets of air. You can take a closer look at the cells, also called lenticels, of a piece of cork by following these instructions.

Materials Needed:

• a small cork
• plain glass microscope slide
• slide cover slip
• sharp knife or razor blade

How to make the microscope slide:

To make a wet mount of the cork, put one drop of water in the center of a plain glass slide – the water droplet should be larger than the slice of cork. Gently set the slice of cork on top of the drop of water (tweezers might be helpful for this). If you are not able to cut a thin enough slice of the whole diameter of the cork, a smaller section will work.

Then, being careful not to move the cork around, lower the coverslip without trapping any air bubbles beneath it.

The water should form a seal around the cork. Use the corner of a paper towel to blot up any excess water at the edges of the coverslip.

To keep the slide from drying out, you can make a seal of petroleum jelly around the coverslip with a toothpick.

Begin with the lowest-power objective to view your slide. Then switch to a higher power objective to see more detail. Use this same wet mount method for the other cell specimens listed below.

You can even check out cells from your own body! The cells on the inside of your cheek are called Squamous Epithelium cells and can be easily viewed with a compound microscope .

• toothpick (flat ones work best)
• slide coverslip
• methylene blue

To make a cheek smear, take a clean toothpick and gently scrape the inside of your cheek. Then wipe that part of the toothpick in the center of your slide.

Hold the coverslip with one end flush on the slide and gently wipe the edge of the coverslip along the middle of the slide’s surface.

This will smear the cells along the slide, making a layer thin enough to view clearly. Let the smear air dry.

Once your smear is dry, add a drop of methylene blue stain to the center of the smear so you will be able to see the cells more clearly.

Gently set a coverslip over the smear and scan your slide under low power to locate the cells, then observe them more closely under high power.

Vegetables are a great way to learn about plants. Did you know that carrots are actually roots, and celery stalks are stems?

• celery stalk (stem)
• a carrot (root)
• plain glass microscope slides
• slide cover slips

Cut a few extremely thin slices out of the middle of the carrot, and some from the middle of the celery stalk. Make a wet mount of the best slice from each vegetable and view them one at a time using your microscope’s 4x objective.

Compare and contrast what you see in each one, then switch to the 10x objective to look a little more closely.

To see details of the amazing structure of plants, use the 40x objective and scan each slide, carefully observing all of the parts and different cells.

Learn even more about plants by studying different sections of real leaves.

• a fresh leaf specimen (use one without many holes or blemishes)

Then, starting at one of the short ends (the edges that you did not cut), tightly roll the leaf section.

Carefully make several very thin slices off one end of the roll with a razor blade or knife. The slices should look almost transparent. T

he cells surrounding the central vein of the leaf are what you will want to look at; depending on the size of the leaf, you might have to cut the slice again so that the central part is the part you will actually see on your slide.

Make a wet mount on a plain slide with the inner part of the leaf section facing up (so the inner cells are visible). Look at the slide with the 10x objective to see the general structure, and higher power to see details of cells.

A tool called a microtome is extremely helpful for preparing specimens for slide mounting. A microtome allows you to expose a small amount of the specimen at a time and cut it off against a solid edge using a very sharp razor blade type knife.

Check out our Slide Making Kit if you’re interested in materials and instructions for making more slides.

We have a variety of microscope prepared slides available both individually and in sets, such as our Biology Slide Set .

Learn more about using your compound microscope by making simple slides using common items from around the house! (Note: This article was written for use with a compound microscope ; however, the technique can be easily adapted for use with a stereo or dissecting microscope as well.)

• clear Scotch tape
• a few granules of salt, sugar, ground coffee, sand, or any other grainy material
• compound microscope like the Home Microscope

To make a slide, tear a 2 ½-3” long piece of Scotch tape and set it sticky side up on the kitchen table or other work area.

Fold over about ½” of the tape on each end to form finger holds on the sides of the slide.

(Note: Because there are several suggestions for things that can be done with these homemade slides throughout this article, you might want to make several slides at once so that you have them ready.)

Place one of your homemade slides on the center of the microscope’s stage, directly over the clear hole. Put one stage clip on one edge of the slide to hold it in place leaving the other end free to move around. Turn your microscope’s light source on, lower the stage, and position the lowest power objective lens over the slide.

Looking through the eyepiece, turn the coarse focus knob until the outlines of the granules become visible. Then turn the fine focus knob to get the image as sharp and clear as possible. Because the tape is thinner than glass microscope slides, you may have to move the slide around some to focus it better – try slightly lifting it up or pressing it down with your fingers. The basic shape of the crystals should be visible at 40x. Now turn the nosepiece so the 10x objective (100x magnification) is positioned over the stage.

Most compound microscopes are parcentered and parfocal. Parcentered means that if you centered your slide while using one objective, it should still be centered even when you switch to another objective. Parfocal means that once you have focused on an object using one objective, the microscope will still be coarsely focused when you switch to a different objective. Because of these features, you should only need to turn the fine focus knob slightly and perhaps move your slide a tiny bit to make sure it is centered and well focused under the new objective lens.

As you slowly turn the fine focus knob you are actually moving in and out of many layers of the specimen, which is why some parts in the field of view may look blurry while some are sharp. This is simply because you are looking at a three-dimensional object and at high magnification the different layers seem much larger than they would without the magnification, even in tiny single-celled organisms!

Compare the shapes, sizes, and colors of the crystals on each of the slides you made. Record your observations on a sheet of paper or in your science notebook. Include information about the slide such as the date, what it is, the magnification level used, and perhaps even a drawing. You can also print out copies of our Microscope Observation Sheets to put in your science notebook.

Hair and thread also work well on homemade tape slides. Collect samples of hair from family members or pets and stick one hair from each sample on a tape slide. Label each slide and view them one at a time with your microscope experimenting with different magnification. Write down your observations about each to see how hairs from humans and animals differ. You can also look at threads or fibers from furniture, rugs or clothing from around your house.

Small insects such as gnats, ants, or fruit flies are interesting to observe with a microscope as well. Stick a dead insect to a tape slide and set it on your microscope stage. Begin with the lowest power and examine all of the insect’s parts. If you discover something interesting, perhaps an eye or part of a leg, look at it more closely with a higher power objective.

To learn more about how the optics of a microscope work, try this experiment: look through a section of a newspaper and find a word that has the letter “e.” Cut out the word and stick it to one of your tape slides with the letters facing up. Observe it under the 4x objective and write down what you see. What does the “e” look like? Is it facing the direction you expected that it would be? Now look at it again with the 10x objective. What can you tell about the lenses of your microscope from this activity? What can you tell about printed material from this experiment?

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Additional Resources

For instructions and materials to make more advanced microscope slides, check out our Microscope Slide Making Kit .

Other articles you might be interested in:

• How to Select a Compound Microscope

Microscope Worksheet: How to Record Microscope Observations

In the field of science, recording observations while performing an experiment is one of the most useful tools available.

Early scientists often kept very detailed journals of the experiments they performed, making entries for each individual experiment and writing down virtually everything they saw.

These entries often included drawings and detailed descriptions as well as the procedures they used, the data they collected, and conclusions drawn from their experimentation.

Our printable Microscope Observation worksheets will help you keep track of the things that you study with your microscope and remember what you have learned.

Blanks are provided for recording general information about each slide, such as the date it was prepared and the stains used, as well as space to write down your observations and circles to do sketches of what you see.

Click here to print out copies of the Microscope Observation worksheet !

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Optional Lab Activities

Lab objectives.

At the conclusion of the lab, the student should be able to:

• identify when a stereomicroscope (dissecting microscope) versus a compound light microscope would be used in the lab
• describe the major differences between light microscopes and electron microscopes
• describe the proper way to carry a microscope
• identify the parts of a compound light microscope
• describe the steps to viewing a slide on a compound light microscope
• determine the total magnification of an object being viewed by a compound light microscope if given the ocular lens and
• objective lens magnifications
• explain why the microscope’s field of view decreases as you increase the magnification

Things you should be able to explain to someone else after this lab:

• Total magnification
• Field of view
• Depth of focus
• Inversion phenomenon

The light microscopes used in this course are sensitive and expensive instruments that are handled by many students throughout the semester. This lab will teach you the information and skills you need to use and care for the microscopes properly.

Many organisms (bacteria) and parts of organisms (cells) that biologists study are too small to be seen with the human eye. We use microscopes to enlarge specimens for our investigation. The word microscope means “to see small” and the first primitive microscope was created in 1595.

There are several types of microscopes but you will be mostly using a compound light microscope . This type of microscope uses visible light focused through two lenses, the ocular and the objective, to view a small specimen. Only cells that are thin enough for light to pass through will be visible with a light microscope in a two dimensional image.

Another microscope that you will use in lab is a stereoscopic or a dissecting microscope . This type of microscope uses visible light view thicker, larger specimens, such as an insect, in 3D. Since you are viewing larger samples, the magnification range of the dissecting microscope is lower than the compound light microscope.

Your instructor will review the parts and functions of the compound light microscopes that we will be using throughout the semester. Fill in the table on the next page to help you remember this important information. You will likely refer back to this page frequently. Here is a picture of a light microscope for you to label and take notes on.

Rules and Instructions for using the Compound Light Microscopes

Your instructor will discuss the use of the microscope with your class. The proper steps to follow for correct focusing will be reviewed. You are to follow the step-by-step sequence as your instructor indicates. Even if you are familiar with this type of microscope, you are still expected to move through the focusing review with the rest of the class.

• Always carry the microscope with 2 hands—place one hand on the microscope arm and the other hand under the microscope base.
• Do not touch the objective lenses (i.e. the tips of the objectives).
• Keep the objectives in the scan position and keep the stage low when adding or removing slides.
• Always look at the microscope from the side when you are making large changes in the height of the stage.
• The objective lenses are to be cleaned only with special lens paper and lens-cleaning fluid.
• Do NOT play handyperson—no microscope is to be disassembled. Report malfunctions to your instructor.
• First clear area on table for microscope—avoid a crowded working area.
• The microscopes are numbered according to where you are sitting. Find the number under your bench and use the corresponding microscope.
• Carry the microscope with TWO hands.
• Secure the electrical cord—don’t let it hang off the table!
• Lower the stage.
• Rotate the scan objective into position over the stage.
• Remove your slide from the stage.
• Clean the slide and objective using the special lens-cleaning fluid and paper provided.
• Center the stage so that it does not project too far to either side.
• Secure the cord by wrapping it under the stage of the microscope..
• Replace the dust cover.
• Return the microscope to the same cubby from which you obtained it making sure to put it in arm out.
• Rotate the objectives so that the scan objective is pointing down at the stage.
• Adjust the stage so that the aperture (the opening in the middle of the stage) is centered.
• Place your slide on the stage, using the stage clamp to secure it. The stage clamp moves only within the horizontal plane of the stage, and it secures the slide by just barely touching the bottom right corner of the slide.
• Center the specimen on your slide under the objective by moving the stage.
• Move the stage up almost as far as it will go, being careful not to let the slide touch the objective lens—look from the side so that you can see how high to raise the stage.
• Use the coarse adjustment knob to move the stage downward until your specimen comes into focus, then sharpen the focus.
• Center the specimen in microscope field by moving the stage.
• Slowly rotate the low power (10X) objective into position.
• Sharpen the focus, if necessary, with the coarse adjustment knob. Only a minimal amount of adjustment is usually necessary.
• Center the specimen in field, if necessary.
• Rotate the high power objective into place very carefully !
• Using the fine adjustment knob only, sharpen focus. Re-center if necessary. (If your specimen has “disappeared”, immediately return to low power and re-center the specimen.)
• When removing a slide, always return the objectives to the scan position and lower the stage before lifting the slide off!

Part 1: Total Magnification

Magnification is the ratio of the image size with the microscope to the actual size of the object. When you say that the magnification is 10, the image you see using the microscope is ten times bigger than viewing the specimen with the naked eye. Remember with a compound light microscope you are magnifying with two lenses, so to calculate the total magnification you multiple the objective magnification by the ocular magnification. View the microscope and use the chart below to calculate total magnification for each lens:

Part 2: Inversion Phenomenon

Obtain a letter “e” slide available in the classroom. View the slide with your eyes, and then place it onto the microscope. Use the focusing sequence to view the slide under low power.

• Draw the letter “e” as it appears when you look at the slide without the microscope.
• Draw the letter “e” as it appears when you look at the slide under the microscope.
• Move your slide to the right using the mechanical stage lever while looking through the oculars. Which way does the “e” move?
• Move your slide away from you using the mechanical stage lever while looking through the oculars. Which way does the “e” move?

State the inversion phenomenon in your own words.

Part 3: Field of View

The field of view is the amount of the specimen you see when you look through the objectives. The field of view decreases at higher magnifications.  

Place a blue plastic ruler across the stage aperture so that the edge of the ruler is visible as a vertical line along the field diameter. Estimate the field size in millimeters for each of the objective lenses.

Scan __________                    Low (10X) __________                    High (40X) __________

Part 4: Depth of Focus

The depth of focus is the thickness of the specimen that remains in focus at a given magnification. Depth of focus decreases at higher magnifications.

Obtain a colored threads slide, and view it under scan or low power. Then, determine which color thread is:

• In the middle
• On the bottom

Hint: using the instructions for focusing, focus on the area where the three threads cross. Use the fine focus to discern the order of the threads.

Part 5: Making a Wet Mount

Throughout the semester, you will be expected to successfully make a number of simple slide preparations called “wet mounts.” The specimen to be observed is placed on a clean slide, a drop or two of water added, and a cover slip carefully placed over the water and specimen. Your instructor will demonstrate this technique.

Make a wet mount of pond water following the procedure below:

• Place a drop of pond water on a clean glass slide using the plastic disposable pipette.
• Cover the pond water on the slide with a coverslip. Try to place the coverslip on at an angle to avid air bubbles.
• Wipe off any excess liquid on your slide.
• Start on the scan objective
• Carefully switch to the low and high objectives as necessary.

Hopefully you will see some live organisms in your pond water. If you view green material, it is probably some sort of plant. Look to see if there is anything moving. In the space below, describe what you are observe under the microscope and draw a simple picture.  

Part 6: Stereoscopic Dissecting Microscope

Your instructor will demonstrate proper use of the dissecting scope. These microscopes generally give a lower magnification than the compound microscope you are using.

View the specimens available at the lab table using the dissecting microscope. Notice that the microscope has two light sources, one from the base and one from above. The specimens are not always mounted on a slide. Also note that when you view objects under the dissecting microscope they are three-dimensional.

Lab Questions

• List two ways that a stereoscopic dissecting microscope differs from a compound microscope.
• Which microscope, the compound light or the dissecting microscope, has a lower magnification?  

Cleaning and Caring for the Microscope

• Describe how and with what you are to clean the lens of the microscope.
• List four things that you are to do when you are finished using the microscope at the end of lab.
• Biology 101 Labs . Authored by : Lynette Hauser . Provided by : Tidewater Community College . Located at : http://www.tcc.edu/ . License : CC BY: Attribution
• BIOL 100 u2013 Survey of Biology. Authored by : Carey Schroyer. Provided by : Open Course Library . Located at : http://opencourselibrary.org/biol-10/ . License : CC BY: Attribution