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Study Sheets

Study sheets will be provided at least two weeks before a test. The study sheet will consist of vocabulary and descriptions of the big ideas taught in class.

All of the material on a study sheet is covered - in the same sequence - during the course of a unit of study.

About 75% of the test questions will consist of study sheet material.

The rest of the test questions will be taken from class activities, section review homework assignments (from the textbook), class discussions, and worksheets. There are at least 25 questions on a test. Most of the time there are more - between 33 and 50.

Important:

Quizzes have 20 or fewer questions. A week's notice is usually given for a quiz. Students should review their homework assignments on the topic, relevant worksheets, and current lab sheets before a quiz. 

A vocabulary quiz is often given a few days before the unit test.

Education is not the filling of a pail,  but the  lighting of a fire. William Butler Yeats

Introduction to the Microscope                            Test Date: TBA

Basic Terms:

• Function of a Microscope: The function of a microscope is to magnify or enlarge the size of tiny objects.
• Magnification: Magnification is the enlargement of an object. A magnification of 100x means that the image you see through the microscope appears 100 times larger than the actual object is.
• Compound Microscope: A compound microscope is a microscope that contains at least two lenses working together to magnify a specimen. In a typical school compound microscope the eyepiece lens and an objective lens create the total magnification of an object.
• Light Microscope: A light microscope uses light as a source of energy for viewing an object. (Some microscopes use electrons as a source of energy for viewing a specimen.)
• Total Magnification: Total magnification is calculated by multiplying the power of the eyepiece (ocular) by the power of the objective lens being used. For example, a school microscope may have an eyepiece magnification of 10x. One of the objective lenses might have a magnification power of 4x. The total magnification of an object as seen through these two lenses together would be 40x. (10 x 4 = 40x)

TOTAL MAGNIFICATION = EYEPIECE x OBJECTIVE LENS

• Resolution: The resolution of a microscope is its ability to show two very close points separately.
• Field of View: The circle of light you see when looking through a light microscope.
• Microscope Carrying Position: Use two hands to carry a microscope. One hand supports the base; the other hand holds the arm.

The Parts of a Compound Light Microscope & Their Functions:

1. The arm supports the upper parts of the microscope and is used to carry the instrument.
2. The base supports the whole microscope and is also used to carry the instrument.
3. The body tube holds the eyepiece on one end and the nosepiece with the objective lenses on the other end. It also provides the pathway for the light to travel from the source through the objective and eyepiece lenses.
4. The coarse adjustment knob is used to focus the microscope when using the low power objective lens.
5. The fine adjustment knob is used to focus the microscope when using the higher power objective lenses.
6. The low power objective lens, located on the nosepiece, provides the least amount of magnification (usually 4x). The low power objective is the shortest of the objective lenses. It is always the first lens you use to view a specimen. Use the coarse adjustment knob with the low power objective lens.
7. The higher power objective lenses, also located on the nosepiece, provide more magnification than the low power objective lens. Most microscopes have two higher power objective lenses. A medium power lens is around 10x and the highest power lens is around 40x. The highest power objective is the longest. Use the fine adjustment knob only with high power or you might crack your slide and damage the lens.
8. The light source or illuminator could be a mirror or electric light bulb. The illuminator provides the light necessary for viewing a specimen.
9. The stage is the platform on which a microscope slide is placed for viewing.
10. The nosepiece holds the objective lenses. It is often called the rotating nosepiece. Rotating the nosepiece enables you to switch from one objective lens to another.
11. The eyepiece or ocular contains the lens, which is located at the top of the body tube. The eyepiece lens is usually 10x.
12. The stage clips hold the slide in place on the stage.
13. The diaphragm is a dial, which regulates the amount of light that can enter the lenses.
14. The stage opening allows light to pass from the light source to the lenses.

1. Tilt the microscope to a comfortable position. Turn on the light switch.
2. Begin with the low power objective "clicked" into place under the body tube. Be sure the largest opening of the diaphragm is directly under the stage opening.
3. Look through the eyepiece to be sure you have a bright white field of view.
4. Place a slide on the stage and center the specimen over the stage opening. Clip the slide in place with the stage clips.
5. Place your hand on the coarse adjustment knob.
6. While looking though the eyepiece, begin to slowly turn the coarse adjustment knob to bring your specimen into clear focus.
7. When the specimen is focused under low power, move the slide if necessary to center the specimen in the field of view.
8. Before switching to a higher power, make sure that what you want to view is in the exact center of the field of view.
9. To view the specimen under medium power, carefully rotate the nosepiece to the medium power objective lens. Use the coarse adjustment – very carefully – to adjust the focus. Check and adjust the placement of the slide if necessary to be sure the specimen is in the center of your field of view.
10. To view the specimen under high power, carefully rotate the nosepiece to the high power objective lens. Notice that the end of the high power objective lens is very close to the slide. DO NOT USE THE COARSE ADJUSTMENT TO FOCUS THE SPECIMEN!!!! Use the fine adjustment knob to focus the specimen.