Biology
CLASS COPY
Introduction to the Microscope
Title: Microscope Mania…Introduction to the Microscope
"Micro" (Greek!) refers to tiny, "scope" refers to view or look. Microscopes are tools used to enlarge images
of small objects so they can be studied. The compound light microscope is an instrument containing two
lenses, which magnifies, and a variety of knobs to resolve (focus) the picture. Because it uses more than one
lens, it is sometimes called the compound microscope - in addition to being referred to as a light microscope.
Purpose: to learn about the proper use and handling of the microscope and practice looking at a variety of
specimen with a microscope.
You will need:
 Compound microscope
 Eye dropper
 Scissors
● Glass slides
● Cover slips
● Microscope diagram
● The letter "e" cut from newsprint
● various specimens to examine
Procedures
I. Microscope Components and Handling
1. Carry the microscope with both hands --- one on the arm and the
other under the base of the microscope. Go to the microscope storage
area and properly transport one microscope to your working area.
Remove the dust cover and store it properly. DO NOT plug it in or
turn it on until instructed.
2. Examine the microscope. Use a microscope diagram sheet and
information provided by your teacher to fill in the names and
functions of each part listed on figure 1.1.
3. Attach the completed diagram in your lab journal.
Fig. 1.1
II. Determining Total Magnification
There are numbers stamped on the eyepiece and on each objective lens. Locate these numbers. You will use
these to calculate the total magnification when using each lens. You calculate by using the steps below.
1.
2.
What is the magnification written on the ocular lens (eye piece)?
What is the magnification written on:
a. the low power objective
b. the medium power objective
c. the high power objective
Introduction to the Microscope
Biology
CLASS COPY
Introduction to the Microscope
3.
The total magnification is determined by multiplying the objective lens power with the ocular lens
power. Copy the table below into your notebook and then calculate the powers of magnification for
each objective lens.
Band color
Eyepiece lens
power
Objective
Power
Power of
Magnification
(X)
=
(X)
=
(X)
=
You are now ready to observe specimens using the microscope. You can do the following procedures
(III-VI) in any order. You only need to complete 3 of the 4 procedures, so choose which ones most
interest you! Be sure to record in your lab notebook what procedure number you are completing.
III. Observing Specimens
1.
2.
3.
4.
5.
6.
Select a slide for viewing from those provided. Place the prepared slide 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 specimen becomes
visible. Then turn the fine focus knob to get the image as sharp and clear as possible. The basic shape
of the specimen should be visible on low power. Now turn the nosepiece so the 10x objective is
positioned over the stage.
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!
In your notebook, cut out and paste a Microscope Mania drawing sheet. Fill in the sheet with the
specimen name and power. You do not need to put your name on the sheet.
Make 3 drawings of the specimen, one on low power, one on medium power and one on high power –
be sure to identify the total magnification under each drawing. Use colored pencils to more accurately
show what you are seeing. You will need a total of 3 Microscope Mania quarter sheets.
Now select one more prepared slide from those available. Sketch it at the highest magnification that is
practical. Be sure to label your drawings and indicate the magnification – use color as well. You will
only need one Microscope Mania sheet to complete this step.
**You should have a total of 4 drawings from this station – One specimen drawn at low, medium and
high (for a total of 3 drawings) and one drawing of a prepared slide at high magnification.**
Introduction to the Microscope
Biology
CLASS COPY
Introduction to the Microscope
IV. Preparing a wet mount of the letter "e”.
1. Cut out a letter "e" from the pieces of newspaper provided.
2. Place it on the glass slide so it looks like an (e).
Figure 1.2
3. Make a wet mount of the letter “e.”
*See diagram on the last page for instructions on how to make a wet mount.
4. Make sure the low objective is pointed toward the stage. Turn on the microscope and place the slide
on the stage; making sure the "e" is facing the normal reading position (see the figure above).
5. Using the course focus, on low power, focus until the "e" can be seen clearly. Use a slide Microscope
Mania information/drawing sheet record your observations and draw what you see. Draw it exactly
how it appears in the microscope. Does it take up the whole circle, part of the circle or some of the
circle, etc.
6. Be sure you label all your drawings with the total magnification represented.
7. As you are looking through the eyepiece, move the slide to the upper right area of the stage. Describe
what happens. Now, move it to the lower left side of the stage. What direction does the image move?
Record these observations in your notebook.
8. Re-center the slide and change the objective to medium power. You will notice the "e" is out of focus.
DO NOT touch the coarse focus knob, instead use the fine focus to resolve the picture. Draw the
image you see of the letter e (or part of it) on high power. Use a Microscope Mania sheet to complete
this step.
9. Locate the diaphragm under the stage. Move it and notice the changes in light intensity as you do.
10. Remove the slide. Carefully remove the cover slip. Throw away the “e”, rinse the slide and cover slip
and carefully dry them with a small piece of paper towel.
**You should have a total of 2 drawings/descriptions for this station: one from #5, and one from #8.**
V. A Hair’s Width
1. Make a wet mount with a few 1/4" to 1/2" pieces of human hair from one person using a drop of water
on a slide, and cover with a cover slip. *See diagram on the last page for instructions on how to make
a wet mount.
2. Observe the hair, draw and write a description of it on a Microscope Mania observation/drawing sheet.
Look at the end that came from the head of a pulled hair (the root). Record what you see on another
observation/drawing sheet. Draw what you see on medium power.
3. Repeat this with a sample of a different colored hair. Record what you see on another Microscope
Mania observation/drawing sheet. Draw what you see on medium power.
4. Find someone with hair that is dyed. Make a wet mount sample and observe/draw. Are there any
differences compared to natural hair that hasn’t been colored?
**You should have a total of 4 drawings/observations from this section: 2 from #2 (the hair and
the root), 1 from #3 (the different colored hair only, not a drawing of the root), 1 from a dyed
hair specimen.**
Introduction to the Microscope
Biology
CLASS COPY
Introduction to the Microscope
VI. Spice it Up
1.
2.
3.
4.
5.
Prepare a dry mount of a sample of salt, sugar and pepper. For each sample, transfer a small amount
onto the slide with tweezers. Remember to start focusing on low power!
Under low power, observe the salt crystals. Focus on medium and then high power. Use a
Microscope Mania sheet to draw what you see.
Examine the sugar sample. Use a Microscope Mania sheet to draw what you see on high power.
Examine the pepper sample. Use a Microscope Mania sheet to draw what you see on high power.
Now choose another spice, make a dry mount and record your observations on high power using a
Microscope Mania sheet.
**You should have a total of 4 drawings/observations from this section: 1 each from step #2-#5**
When you are finished with a microscope - turn it off. Clean up your slides and cover slips and return them to
the box. Place the low power objective in place and lower the body tube. Cover the scope with the dust cover.
Place the scope back in its proper place.
How to Prepare a wet mount for a specimen
Procedure
1.
2.
3.
4.
Place the specimen on the microscope slide.
Place one drop of water on the center of the specimen.
While holding the cover slip upright, carefully place one edge of the cover slip next to the water.
Slowly lower the upper edge of the cover slip onto the water. The objective is to minimize or eliminate
air bubbles under the cover slip.
5. After you have covered the specimen with a cover slip, an absorbent towel can be placed at the edge of
the cover slip to draw out some of the water, further flattening the wet mount slide.
Introduction to the Microscope
Biology
CLASS COPY
Introduction to the Microscope
Conclusions: Answer the following questions in your notebook. You only need to answer the questions about
the procedures you did. The answers are based on the work you have just completed using the microscope.
Questions (Observing Specimens)
1. What difficulty did you have when you observed your samples under the microscope?
2. What surprised you about what you saw under the high power that you couldn’t see under low power?
Questions (The letter “e”)
1. What happens to our view of an image as you increase the power of magnification?
2. What did you observe about the orientation of the letter “e” when viewed through the microscope?
3. Why would you want to wet mount a specimen?
Questions (A hair’s width):
1. Did you see any differences between the hair that had been dyed and that which was a natural color?
2. Describe what the root looked like. Did this surprise you?
Questions (Spice it up)
1. What does table salt look like?
2. What did the sugar look like?
3. What was unique about the spice you chose?
4. Why did you need to make a dry mount of these instead of a wet mount?
Introduction to the Microscope
Biology
Introduction to the Microscope
Introduction to the Microscope
CLASS COPY