Microscope Lab - Using the Microscope and Slide Preparation       Name _______________________

Examine the microscope and familiarize yourself with the parts of the microscope.

1. Magnification

The magnification written on the ocular lens (eyepiece) is _____________

The magnification on the Scanning objective ________ Low Power Objective ________ High Power Objective _______

What is the total magnification for each lens (multiply ocular times objective)

Scanning _____________ Low Power ______________ High Power ________________

2. Diaphragm

Examine the diaphragm, what are the numbers written on it? ____________________

Which setting makes the specimen the lightest? ________________ The darkest? _______________

3. Lenses

Twist the ocular lens, does yours have a pointer? _____________ What is the purpose of the pointer?

What happens to your viewing field if you do not have an objective fully clicked into place.

4. Viewing a Slide

Obtain a prepared e slide. Focus the slide first with the scanning objective, then click to lower power and focus again. Finally, focus the slide under high power. Remember, at high power, you should ONLY use the fine adjustment knob.

Draw the e exactly as it appears in your viewing field for each magnification. The circles below represent your viewing field. The e should take up as much space in the drawing as it does in your viewing field while you're looking at it.

5. Depth Perception

Obtain a prepared thread slide. You will only need to view it under scanning at this point. Your task is to figure out which thread is on top, which is in the middle, and which is on bottom. You should notice that as you focus the thread, different thread will come into focus at different times. The one that comes into focus the first should be the top thread.

If your thread is made of different colors, what is the color order of your threads?_____________________________________________

Why do only parts of the thread appear sharp and clear at any given time? __________________________________________________

With the slide holding the thread, put your high power objective in place. Observe the thread carefully as you slowly open and close the diaphragm.

What differences did you observe under the various diaphragm settings? ___________________________________________________

6. Making measurements with a microscope

Put a clear plastic ruler on the microscope stage so you can see the millimeter scale under scanning power. Place one millimeter marking of your ruler at the far left hand side of the scanning power field. You should see other millimeter markings in your field of view. This means that your scanning power field can be measured as some millimeter is diameter.

To the nearest 0.1 mm, what is the diameter of the scanning power field of view. ________________________________

With the ruler in place, change to the low power objective and measure the diameter of the low power field of view.

To the nearest 0.1 mm, what is the diameter of the low power field of view. ___________________________________

The high power cannot be accurately measured using a millimeter ruler. This can be calculated using the magnifications of the high and low power objectives. Divide the high power magnification by the low power magnification to determine how many times larger low power field is than your high power field.

What is the calculated diameter of your high power field of view? ____________________________________________

Many specimens you will observe under the microscope will be smaller than 1 mm in size. Because of this, microscopic measurements are often expressed in microns (mm or micrometers). One millimeter equals 1,000 microns.

What are the diameters of your scanning, low and high power fields in microns? ________________________________________

7. Making a Wet Mount of a Slide

1. Gather a sample of cheek cells using a toothpick. If your specimen is too thick, then the coverslip will wobble on top of the sample like a see-saw, and you will not be able to view it under High Power.

2. Place ONE drop of water directly over the cheek cells. If you put too much water, then the coverslip will float on top of the water, making it hard to draw the specimen, because they might actually float away. (Plus too much water is messy)

3. Place the coverslip at a 45 degree angle (approximately) with one edge touching the water drop and then gently let go. Performed correctly the coverslip will perfectly fall over the specimen.

Draw the specimen as it appears in your viewing field under scanning, low and high power.

8. Staining a Specimen

1. Place one drop of stain (methylene blue) on the edge of the coverslip. Caution: Methylene Blue will stain clothes and skin!

2. Place the flat edge of a piece of paper towel on the opposite side of the coverlip. The paper towel will draw the water out from under the coverslip, and the cohesion of water will draw the stain under the slide.

3. As soon as the stain has covered the area containing the specimen, you are finished. The stain does not need to be under the entire coverslip. If the stain does not cover as needed, get a new piece of paper towel and add more stain until it does.

4. Be sure to wipe off the excess stain with a paper towel.

Draw your specimen as it appears under low power. Used color pencils to show how the stain appears. It may appear darker or lighter in spots. Use shading to show darker and lighter spots.

What is the diameter of a cheek cell in microns? _____________________________________

9. Identify plant cells under a microscope

1. Pull a single leaf from the elodea plants in the beaker supplied by your teacher.

2. Place ONE drop of water directly over the elodea leaf. If you put too much water, then the coverslip will float on top of the water, making it hard to draw the specimen, because they might actually float away. (Plus too much water is messy)

3. Place the coverslip at a 45 degree angle (approximately) with one edge touching the water drop and then gently let go. Performed correctly the coverslip will perfectly fall over the specimen.

Draw the specimen as it appears in your viewing field under scanning, low and high power.

What are the dimensions of an elodea cell in microns? ______________________________________