The Microscope 5356795 - Films On Demand - Loginfod.infobase.com/HTTP/180307.pdf · · 2016-04-12compound light microscope, ... • Identify and state the functions of the following

Visual Learning Company 1-800-453-848125 Union Streetwww.visuallearningco.com Brandon, Vermont

Editors:Brian A. Jerome, Ph.D.Stephanie Zak Jerome

Assistant Editors:Louise MarrierHannah Fjeld

Graphics:Dean Ladago

Fred Thodal

Teacher’s GuideMiddle School

The Microscope

Visual Learning Company 1-800-453-8481 www.visuallearningco.com

The MicroscopeThe Microscope

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Use and Copyright

The purchase of this video program entitles the user the right to reproduce or duplicate, in whole or in part, this teacher’s guide and the blackline master handouts for the purpose of teaching in conjunction with this video, The Microscope. The right is restricted only for use with this video program. Any reproduction or duplication, in whole or in part, of this guide and student masters for any purpose other than for use with this video program is prohibited.

The video and this teacher’s guide are the exclusive property of the copyright holder. Copying, transmitting or reproducing in any form, or by any means, without prior written permission from the copyright holder is prohibited (Title 17, U.S. Code Sections 501 and 506).

Copyright © 2006

ISBN 978-1-59234-143-8

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The Microscope

Visual Learning Company1-800-453-8481www.visuallearningco.com

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The Microscope

Table of ContentsPage

A Message From Our Company

National Standards Correlations

Student Learning Objectives

Assessment

Introducing the Video

Video Viewing Suggestions

Video Script

Student Assessments and Activities

Answers to Student Assessments

Answers to Student Activities

Assessment and Student Activity Masters

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The video and accompanying teacher’s guide are for instructional use only. In showing these programs, no admission charges are to be incurred. The programs are to be utilized in face-to-face classroom instructional settings, library settings, or similar instructional settings.

Duplication rights are available, but must be negotiated with theVisual Learning Company.

Television, cable or satellite rights are also available, but must be negotiated with the Visual Learning Company.

Closed circuit rights are available, and are defi ned as the use of the program beyond a single classroom but within a single campus. Institutions wishing to utilize the program in multiple campuses must purchase the multiple campus version of the program, available at a slightly higher fee.

Discounts may be granted to institutions interested in purchasing programs in large quantities. These discounts may be negotiated with the Visual Learning Company.

Viewing Clearances

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The Microscope


Dear Educator:

Thank you for your interest in the educational videos produced by the Visual Learning Company. We are a Vermont-based, family owned and operated business specializing in the production of quality educational science videos and materials.

We have a long family tradition of education. Our grandmothers graduated from normal school in the 1920’s to become teachers. Brian’s mother was an elementary teacher and guidance counselor, and his father was a high school teacher and superintendent. This family tradition inspired Brian to become a science teacher, and to earn a Ph.D. in education, and led Stephanie to work on science educational programs at NASA.

In developing this video, accompanying teacher’s guide, and student activities, our goal is to provide educators with the highest quality materials, thus enabling students to be successful. In this era of more demanding standards and assessment requirements, supplementary materials need to be curricular and standards based - this is what we do!

Our videos and accompanying materials focus on the key concepts and vocabulary required by national and state standards and goals. It is our mission to help students meet these goals and standards, while experiencing the joy and thrill of science.

Sincerely,

Brian and Stephanie Jerome

A Message from our Company. . .



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National Standards CorrelationsNational Science Education Standards (Content standards: 5-8, National Academy of Sciences, c. 1996)

Benchmarks for Science Literacy (Project 2061 – AAAS, c. 1993)

Science as Inquiry (Content Standard A)Use appropriate tools and techniques to gather, analyze, and interpret data.

• The use of tools and techniques, including mathematics, will be guided by the questions asked and the investigations students design.

Life Science (Content Standard C)• All organisms are composed of cells- the fundamental unit of life. Most organisms are single cells; other organisms, including humans, are multicellular.

Technology and Science (3A)

By the end of the 5th grade, students should know that:

• Measuring instruments can be used to gather accurate information for making scientifi c comparisons of objects and events, and for designing and constructing things that will work properly.

The Living Environment (5C)

By the end of the 8th grade, students should know that:

• All living things are composed of cells, from just one to many millions, whose details usually are visible only through a microscope. Different body tissues and organs are made up of different kinds of cells. The cells in similar tissues and organs in other animals are similar to those in human beings but differ somewhat from cells found in plants.

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The Microscope


Student Learning ObjectivesUpon viewing the video and completing the enclosed student activities, students will be able to do the following:

• Describe that the basic function of a microscope is to make small objects look larger.

• Understand that microscopes have played a very important role in furthering scientifi c understanding of cells and many other things too small to be seen with the naked eye.

• Compare the design and use of different types of microscopes including the compound light microscope, stereo microscope, and electron microscope.

• Differentiate between the functions of a scanning electron microscope and a transmission electron microscope.

• Defi ne magnifi cation as the ability to make things appear larger than they actually are.

• Generally explain how a compound light microscope uses lenses and light to magnify an image.

• Identify and state the functions of the following parts of a compound light microscope: base, arm, light source, stage, diaphragm, objective lenses, nosepiece, body tube, eyepiece, coarse adjustment, and fi ne adjustment.

• Demonstrate how to safely view a prepared slide under low power and high power magnifi cation.

• Demonstrate how to safely carry a microscope with two hands, with one hand always under the base.

• Understand that images viewed under the microscope appear upside down and backwards in relation to their actual position.



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Assessment

Preliminary Assessment:The Preliminary Assessment, provided in the Student Masters section, is an assessment tool designed to gain an understanding of students’ pre-existing knowledge. It can also be used as a benchmark upon which to assess student progress based on the objectives stated on the previous pages.

Video Review:The Video Review, provided in the Student Masters section, can be used as an assessment tool or as a student activity. There are two main parts. The fi rst part contains questions that can be answered during the video. The second series of ten questions consists of a video quiz to be answered at the conclusion of the video.

Post Assessment:The Post Assessment, provided in the Student Masters section, can be utilized as an assessment tool following completion of the video and student activities. The results of the Post Assessment can be compared against the results of the Preliminary Assessment to evaluate student progress.

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The Microscope


Introducing the Video

Video Viewing SuggestionsThe student Master “Video Review” is provided for distribution to students. You may choose to have your students complete this Master while viewing the program or to do so upon its conclusion.

The program is approximately twenty minutes in length and includes a ten question video quiz. Answers are not provided to the Video Quiz on the video, but are included in this teacher’s guide. You may choose to grade student quizzes as an assessment tool or to review the answers in class.

The video is content-rich with numerous vocabulary words. For this reason you may want to periodically stop the video to review and discuss new terminology and concepts.

Before showing the video to your students, cut out a picture of someone’s face from a magazine, and tape it to the blackboard. Try to fi nd a picture of someone the students will readily recognize. Make sure the picture is not bigger than a quarter of an inch (about .7 centimeters). Ask students sitting at their desks if they can tell what the picture is. Next ask a volunteer to come forward to see if they can identify the face of the person when standing 1 meter away. Next give them a magnifying glass to identify the person. Discuss the concept of magnifi cation.

Next ask the class what instrument they would need to identify the eye color of the person. Explain that the image could be put under a compound light microscope. Show your students a compound light microscope. Place the photo on a slide and make a wet mount of it. Put the slide on the stage and focus the image under low power. Have a student volunteer come forward to look at the image through the microscope. Ask the student if they can identify the eye color of the person. Ask students to list the types of tasks for which microscopes are useful. Tell students to pay close attention to learn more about how microscopes work, and how to safely use a microscope.



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Video Script: The Microscope 1. This pond is full of millions of tiny organisms too small to be seen with the naked

eye. 2. The mouth of this dog contains a wide range of organisms called bacteria. 3. Even though you can’t see them, dozens of different kinds of tiny living things

live in this single drop of water taken from this wetland. 4. And the blood coming from this cut contains thousands of tiny cells. 5. How do we know about all these different living things? 6. And how is it possible for scientists, and even you as a science student, to

observe these fascinating living things? 7. The answer lies in the use of a remarkable tool – the microscope. 8. What exactly is a microscope? Simply put, a microscope is an instrument that

makes small objects look larger. 9. A microscope produces an enlarged image of something that might otherwise be

too small to be seen with the naked eye.10. During the next few minutes we are going to take a look at some of the different

types of microscopes.11. And we are going to discuss how you can effectively and safely use a

microscope in your science classroom.12. But, fi rst let us take a quick look at the development of early microscopes.13. Graphic Transition – Early Microscopes14. Until the late 1500s it was not possible to see very small objects, such as cells.15. In fact, people weren’t even sure if cells existed.16. In 1590, the invention of the microscope enabled people to look at very small

objects never before seen.17. Early microscopes consisted of simple lenses inserted in a tube.18. The fi rst compound light microscopes consisted of a tube with a lens at each

end. 19. We will talk more about compound light microscopes later.20. In 1663, the English biologist, Robert Hooke, improved on the design of early

microscopes, thus enabling him to make one of the most important discoveries in the history of biology.

21. By cutting a very thin slice of cork, and placing the section under a microscope, he made an important discovery.

22. You Decide! What are these structures Hooke saw?23. These structures are cork cells. The discovery of cells served as the basis

for other scientists such as Antonie von Leeuwenhoek and Mathias Schleiden to develop a more thorough understanding of cells, which we now know are the basic unit of life.

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Script Cont.24. Microscopes have played a critical role in helping scientists further our

understanding of not only cells, . . . 25. . . . but of other living and non-living things too small to be seen with the naked

eye.26. Graphic Transition – Types of Microscopes27. Today, scientists have access to a wide range of different kinds of microscopes.28. These microscopes vary in the level of complexity, cost, and the type of work

they can perform.29. Perhaps you have seen a microscope similar to this in your science classroom.30. This type of microscope is generally referred to as a compound light

microscope.31. Compound light microscopes have more than one lens, and use light to magnify

an object.32. Using a single lens, a magnifying glass produces an image a few times larger

than an object.33. But a compound microscope uses two or more lenses to create an image that is

up to one thousand times larger than the actual object.34. Another type of microscope you may have seen in your science classroom is

called a stereomicroscope.35. This type of microscope is similar to a compound light microscope but it is used

to closely study large objects such as rocks, fl owers, and other kinds of living things.

36. A very sophisticated type of microscope that has greater ability to magnify objects is called the electron microscope, as seen here.

37. Instead of light, the electron microscope sends a beam of tiny particles called electrons over the surface of a specimen to create an image.

38. This creates a detailed three-dimensional image of the surface of a specimen, and can enlarge it up to 150,000 times.

39. Scanning Electron Microscopes are quite expensive and are found at universities and other institutions that conduct scientifi c research.

40. Another type of electron microscope called the Transmission Electron Microscope actually passes electrons through a very thinly sliced specimen.

41. Because this microscope can enlarge a specimen up to 500,000 times its actual size, it is very useful for studying the internal structures of cells.

42. Graphic Transition - The Compound Light Microscope 43. This is what the image of a compound microscope looks like without light.



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Script Cont.44. And here is the image with the light on. As you can see, light is essential for a

compound light microscope to work properly.45. Magnifi cation is the ability to make things appear larger than they actually are.46. Lenses are essential for the magnifi cation of specimens. A close look at a lens,

such as the one in a magnifying glass reveals that the lens is not fl at, but is thicker in the middle than at the edges.

47. When light passes through the lens it is bent and magnifi ed, making the object appear larger than it really is.

48. In a compound light microscope, light passes up through a specimen and then through two or more lenses before reaching the eye.

49. The total magnifi cation of the microscope is computed by multiplying the magnifi cation of the different lenses.

50. For example, let us say that the magnifi cation of the lower lens is 40,…51. …and the magnifi cation of the upper lens is 10.52. You Compute! What is the total magnifi cation?53. That is right, by multiplying 10 by 40 we get a total magnifi cation of 400.54. This means that these bacteria are magnifi ed 400 times their actual size.55. Graphic Transition – Parts of the Compound Microscope56. Each part of a car has a specifi c name and function. It is useful to know the name

of the part and to understand the job it performs.57. The same holds true for the compound light microscope in your science

classroom.58. Let us take a minute to discuss the parts of the microscope.59. The base supports the microscope and keeps it stable.60. The base is attached to the arm. The arm support the body tube seen here.61. Near the base is the light source or mirror.62. If a mirror is used, it is necessary to use a light which the mirror refl ects upward

through the specimen.63. If an actual light is present, an on/off switch is adjacent to it.64. This fl at, black area is called the stage. The stage supports the slide being

viewed.65. In the middle of the stage is a hole which allows for the passage of light originating

from below.66. Beneath the stage is a mechanism called the diaphragm.67. The diaphragm is an adjustment which controls the amount of light passing

through the opening of the stage.68. These silver tubes are lenses called objective lenses.

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The Microscope


Script Cont.69. This particular microscope has four objective lenses.70. On the side of each objective lens is a number.71. This lens has the number 4.72. You Decide! What do you think the 4 means?73. That is right, the 4 means this lens has a magnifi cation of 4 times, also referred to

as 4 power.74. The smallest objective is sometimes referred to as the low power objective. In this

case, the 10 power objective is the low power objective..75. And the larger objective is sometimes referred to as the high power objective.76. This silver circular structure is called the nosepiece. The nosepiece holds the

objective lenses above the stage, and rotates them so different objective lenses may be used.

77. The nosepiece is attached to the body tube. The body tube separates the nosepiece from the eyepiece and allows for the passage of light from below.

78. The eyepiece lens on this particular microscope has a magnifi cation of ten.79. This large circular knob is the coarse adjustment.80. The coarse adjustment moves the stage in bigger increments to bring the

specimen into focus.81. It is designed to be used when using the low power objective.82. The smaller knob is called the fi ne adjustment and is used when focusing the high

power objective.83. Graphic Transition – Using the Microscope84. The microscopes in your science classroom are some of the most expensive and

delicate tools in your school.85. Microscopes are built to last many years, but only if they are used carefully and

correctly.86. Before using the microscope create a clean and clear workspace, free of books,

bags, clothing, and food.87. When carrying the microscope always use two hands.88. Grasp the arm of the microscope with one hand, and place the other hand under

the base.89. Place the microscope well back from the edge of the table with the arm toward

you.90. Plug in the microscope.91. Using the coarse adjustment, increase the distance between the stage and the

objective lenses.92. Rotate the nosepiece until the lowest power objective – the shortest lens, clicks

into place and is aligned over the hole in the stage.



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Script Cont. 93. Look through the eyepiece and carefully adjust the diaphragm so the maximum

amount of light is coming through the nosepiece. 94. Obtain a prepared slide from your teacher. 95. Keep in mind that slides are made of glass. If they are dropped even a short

distance they will break. 96. Carefully place the slide on the stage, and position it under or between the stage

clips while positioning the portion of the slide containing the specimen over the hole in the stage.

97. Once you have positioned the slide, look at the stage from the side. 98. While looking through the eyepiece, very slowly raise the body tube by turning

the coarse adjustment knob until the specimen comes into focus. 99. Let us say you want to get a closer look of the specimen. In other words you

want to increase the magnifi cation by switching to a higher power objective.100. Once again, look at the stage from the side.101. Carefully rotate the nosepiece until the high power objective lens clicks into

place. Be very careful the lens does not touch the slide, as it may break the slide and damage the lens.

102. Turn the fi ne adjustment a very small amount to bring the specimen in to focus.103. Graphic Transition- Helpful Hints for the Microscope104. This is the letter “e” as seen under low power. Notice that it appears upside

down.105. You Observe! What do you observe through the eyepiece when we move the

slide to the left?106. As you can see, when the slide is moved to the left, it looks like it is moving to the

right through the eyepiece. 107. This is a strange thing to get used to when working with the compound light

microscope.108. Images as seen under the microscope appear upside down and backward.109. Another thing to keep in mind while using the microscope is that the brightest

light, or most amount of light, is not always the best to use.110. The diaphragm controls the amount of light going through a specimen.111. Experiment with the control of the diaphragm to see how varying amounts of light

effect your view of the specimen. 112. Quite often, less light creates a greater contrast enabling you to see structures

not visible with large amounts of light.113. Some microscopes also contain an adjustment controlling the intensity of light.114. One exciting thing to do with a microscope is to view specimens collected on

your own.

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The Microscope


Script Cont.115. Your instructor can show you how to collect specimens and to create a wet mount

with a clean slide and a cover slip.116. Graphic Transition- Summing Up117. During the past few minutes, we have taken a look at some of the fascinating

aspects of microscopes.118. We began by discussing some of the features of early microscopes...119. ...and how they were instrumental in developing early knowledge of microscopic

life.120. We also talked about some of the different types of microscopes including the

Scanning Electron Microscope,121. ...and the Transmission Electron Microscope.122. More specifi cally, the safe use of the compound light microscope was

demonstrated.123. The parts of the compound light microscope and their function were also

highlighted.124. Finally, we pointed out some helpful hints in using the microscope.125. So the next time you use a microscope in your school science lab, think about

some of the things we discussed during the past few minutes,126. You just might think about microscopes a little differently.127. Graphic Transition- Video QuizFill in the correct word to complete the sentence. Good luck and let us get started.

1. Robert Hooke used a microscope to discover _____.2. An _________ microscope uses a stream of electrons to create an image. 3. This is a ___________ light microscope.4. _______ are used to magnify a specimen in this microscope.5. _________ is the ability to make things appear larger.6. This fl at black area is the _______.7. These silver tubes are __________ lenses.8. This large knob is the _______ adjustment.9. Always use ____ hands when carrying a microscope.10. Images under the microscope appear ________ down and backward.

Answers can be found on page 17.



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• Parts of the Microscope

• Making a Wet Mount

• Cells Under the Microscope

• Vocabulary of The Microscope• Vocabulary of The Microscope• Vocabulary of

Student Assessments and Activities

Assessment Masters:

• Preliminary Assessment

• Video Review

• Post Assessment

Student Activity Masters:

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The Microscope


Answers to Student AssessmentsPreliminary Assessment (pgs. 20-21)

1. cells 2. electron 3. compound 4. lenses 5. magnifi cation 6. stage 7. objective 8. coarse 9. two10. upside

Video Review (pg. 22)

Post Assessment (pgs. 23-24)

Video Quiz (p. 22)

1. light 2. small 3. cells 4. lenses 5. compound 6. electron 7. multiply 8. diaphragm 9. eyepiece10. glass11. true12. false13. false14. true15. false16. false17. true18. true19. false20. false

1. electron 2. eyepiece 3. light 4. diaphragm 5. multiply 6. glass 7. compound 8. cells 9. small10. lenses11. true12. false13. true14. false15. false16. true17. false18. true19. false20. false

1. The structures that Hooke saw were cork cells. Hooke is credited with the discovery of the cell, which other scientists then further studied.2. The total magnifi cation is 400x. This is computed by multiplying the magnifi cation on the lenses. In this case 10 * 40 = 400.3. The 4 on the side of the lens means the lens has a magnifi cation of four times.4. When the slide moves to the left, the “e” appeared to be moving to the right. This means that the microscope creates an image that is backwards and upside down from the actual image.



Answers to Student Activities

1.Eyepiece

2. Body Tube

3. Nosepiece

4.Objective Lenses 5. Arm

6. Stage

7. Diaphragm 8. Coarse Adjustment

9. Fine Adjustment

10. Light Source

11. Base

Parts of the Microscope (p. 25)

Making a Wet Mount (p. 26-27)

Cells Under the Microscope (p. 28-29)a) Drawings will vary.b) Drawings will varyc) The cork cells are rectangular and stiff-looking. They are regularly spaced. Tell your students these are dead cells.d) Drawings will vary.e) By moving the fi ne adjustment knob very, very slowly, you can focus on different layers of onion cells. You can also see different features of the cells that occur at different levels.f) Drawings will vary.g) Adding a drop of stain to your wet mount allows you to see more detail within the cell. The stain may have allowed you to identify the nucleus and the cell membrane.h) The onion cells contain cytoplasm, a nucleus, and a cell membrane, while the cork cells do not. Both types of cells have a cell wall, and have similar shape. They are both plant cells.i) You can tell that the cork cells were nonliving because, aside from the cell wall, no cell structures were visible in the cork cells, and no cytoplasm was visible.

a) It is important to watch from the side as you lower the lens because if you are not watching, the lens could hit the slide, and either the slide or the lens can break.b) Drawings will vary. The “e” should appear upside down and backwards.c) When the slide is moved left, it appears to move right. When it is moved right, it appears to move left.d) When the slide is moved away from you, it appears to move toward you and vice versa.e) The diaphragm controls the amount of light passing through the slide. By adjusting the amount of light the contrast and clarity of the image can be controlled.f) Drawings will vary. Only a small part of the “e” will show.g) The low power lens has a larger fi eld of view, and the image through the low power lens is much brighter.

Vocabulary of the Microscope (p. 30) 1. c - magnifi cation 2. g - base 3. e - lens 4. h - objective lenses 5. b - compound light microscope 6. i - nosepiece 7. d - electron microscope 8. a - microscope 9. j - stereo microscope10. f - fi ne adjustment

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Assessment and Student

Activity Masters

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NameThe Microscope

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Preliminary AssessmentDirections: Fill in the blank with the correct word. A list of possible answers is provided at the bottom of the page.

1. Without _________ , a compound light microscope will not function.

2. A microscope allows you to see an image of something that is otherwise too __________ to see with the naked eye.

3. ________ were discovered using a microscope.

4. A compound microscope uses a series of __________ .

5. In most classroom science labs, you will fi nd a ___________ light microscope.

6. Some of the most sophisticated, expensive microscopes are ____________ microscopes.

7. To fi nd the total magnifi cation of a series of lenses, you must ___________ the magnifi cation of all the lenses.

8. On a compound light microscope, the ____________ controls the amount of light passing through the stage.

9. The ___________ is the part of the microscope you look through. It also plays a role in magnifying the image.

10. Microscope slides are commonly made of __________ .

electronglassdiaphragmsmalllight

eyepiecemultiplycompoundlensescells

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NameThe Microscope

T F

Preliminary AssessmentDirections: Decide whether the statement is true (T) or false (F).

T F

T F

T F

T F

T F

T F

T F

T F

T F

11. Before the invention of the microscope, it was not possible to see cells.

12. Microscopes are generally cheap and easily replaceable.

13. A magnifying glass can enlarge an image much more than a compound light microscope.

14. A compound light microscope uses a series of lenses to magnify an object.

15. A lens used to magnify an image is thinner in the middle and thicker at the edges.

16. To compute the total magnifi cation of multiple lenses, you must simply add the magnifying factor of each lens.

17. The surface where you place the slide on a compound light microscope is called the stage.

18. The silver tubes attached to the nosepiece on a compound light microscope are lenses called objective lenses.

19. A low power objective magnifi es an object the greatest.

20. Microscope slides are almost always made of plastic and don’t break easily.

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NameThe Microscope

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Video ReviewDirections: During the course of the program, answer the questions as they are presented in the video. At the end of the video, answer the Video Quiz questions.

You Decide! 1. What are these structures Hooke saw?

You Compute! 2. What is the total magnifi cation?

You Decide! 3. What do you think the 4 means?

You Observe! 4. What do you observe through the eyepiece when we move the slide to the left?

Video Quiz:

1. Robert Hooke used a microscope to discover ________ .

2. An ___________ microscope uses a stream of electrons to create an image.

3. This is a ____________ light microscope.

4. __________ are used to magnify a specimen in this microscope.

5. _________________ is the ability to make things appear larger.

6. This fl at black area is the ________ .

7. These silver tubes are _____________ lenses.

8. This large knob is the _________ adjustment.

9. Always use ______ hands when carrying a microscope.

10. Images under the microscope appear ___________ down and backward.

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Post AssessmentDirections: Fill in the blank with the correct word. A list of possible answers is provided at the bottom of the page.

1. Some of the most sophisticated, expensive microscopes are ____________ microscopes.

2. The ___________ is the part of the microscope you look through. It also plays a role in magnifying the image.

3. Without _________ , a compound light microscope will not function.

4. On a compound light microscope, the ____________ controls the amount of light passing through the stage.

5. To fi nd the total magnifi cation of a series of lenses, you must ___________ the magnifi cation of all the lenses.

6. Microscope slides are commonly made of __________ .

7. In most classroom science labs, you will fi nd a ___________ light microscope.

8. ___________ were discovered using a microscope.

9. A microscope allows you to see an image of something that is otherwise too ___________ to see with the naked eye.

10. A compound microscope uses a series of __________ .

electronglassdiaphragmsmalllight

eyepiecemultiplycompoundlensescells

24©2006

NameThe Microscope

25

Post AssessmentDirections: Decide whether the statement is true (T) or false (F).

T F

T F

T F

T F

T F

T F

T F

T F

T F

T F

11. A compound light microscope uses a series of lenses to magnify an object.

12. Microscope slides are almost always made of plastic and don’t break easily.

13. The surface where you place the slide on a compound light microscope is called the stage.

14. A low power objective magnifi es an object the greatest.

15. Microscopes are generally cheap and easily replaceable.

16. The silver tubes attached to the nosepiece on a compound light microscope are lenses called objective lenses.

17. A lens used to magnify an image is thinner in the middle and thicker at the edges.

18. Before the invention of the microscope, it was not possible to see cells.

19. To compute the total magnifi cation of multiple lenses, you must simply add the magnifying factor of each lens.

20. A magnifying glass can enlarge an image much more than a compound light microscope.

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NameThe Microscope

Parts of the MicroscopeBackground:The microscope is a highly specialized tool with many different parts. Each piece of the microscope plays an essential part in the microscope’s function. In your classroom, you probably will use a compound light microscope. A compound light microscope shines a beam of light through a thin sample. The image is then magnifi ed by two lenses, the compound lens and the eyepiece. A compound light microscope can magnify an image up to 1000 times its original size!

Directions:Below is an image of a compound light microscope. Label all the parts, being sure to include: base; arm; light source; eyepiece; compound lenses; coarse adjustment; fi ne adjustment; diaphragm; nosepiece; stage; and body tube.

1. _____________

2. _____________

3. _____________

4. _____________ 5. _____________

6. _____________

7. _____________ 8. _____________

9. _____________

10. _____________

11. _____________

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Making a Wet MountBackground:You’ve probably used a microscope to look at slides before. Microscope slides that are sealed and preserved are called prepared slides. You can also make your own temporary slides in the science lab. A temporary slide is called a wet mount, because the cover slip rests on top of a drop of water. You can only use a wet mount for a short period of time because it will dry out. In this activity you will learn how to make a wet mount and practice using the microscope to view slides.

Directions:1. Cut out a lower case “e” from the newspaper. Be sure that the square is no larger than one centimeter, and that the “e” is in the middle.

2. Place the “e” in the center of a clean microscope slide. Gently drop one drop of water on top of the square of newsprint using your pipette or dropper. Be careful not to touch the pipette or dropper to the slide, because it will stick to the paper.

3. Next you will cover the mount with a cover slip. Hold the cover slip between your thumb and forefi nger at a 45º angle, and slowly move it toward one edge of the drop. When the water touches the cover slip, it will spread to the edge. Carefully lower the cover slip until it is fl at on the newsprint. It should rest on top of the water without touching the slide. A good wet mount has no bubbles. If you do see some bubbles, don’t press on the cover slip because the water will be pressed out rather than the bubbles. If your wet mount has a lot of bubbles, begin again from step 2.

4. Place your wet mount onto the stage of your microscope. Make sure the “e” is positioned as if you would read it. Use the stage clips to hold the slide in place.

5. Position the low power objective directly over the stage. Turn the microscope on using the On/Off switch. Watching from the side, turn the coarse adjustment knob until the lens is only half a centimeter above the slide.

a) Why is it important to watch from the side as you lower the lens?

Materials:Microscope, clean microscope slides, cover slips, a sheet of newspaper, water, a pipette or dropper, and scissors

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Making a Wet Mount cont.6. Looking into the eyepiece, slowly raise the lens by turning the coarse adjustment knob until the “e” comes into focus. b) Draw the letter “e” exactly as it appears through the microscope.

7. Move the slide to the left. Then move the slide to the right.

c) What happens as you watch through the eyepiece?

d) What happens when you move the slide backward? and forward?

8. Reposition the slide with the “e” in focus and centered on the stage. Change the diaphragm to each of its settings as you observe the “e.” Adjust it to provide the best contrast and illumination.

e) What does the diaphragm control?

9. When the “e” is as clear as possible, carefully rotate the nosepiece until the high power objective clicks into position. Make sure you watch from the side, so that the lens does not hit the slide and ruin your mount.

10. Using only the fi ne adjustment knob, focus on the “e.” You can also adjust the brightness and contrast of the image using the diaphragm. Obtain the best possible image you can.

f) Draw the image exactly as you see it.

g) Which lens has a larger fi eld of view? Which is brighter?

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29

Cells Under the MicroscopeBackground:Its likely that you already know that all living things are made up of cells. However, you may never have seen what a cell looks like up close. In order to see cells, we

Materials:a microscope, clean slides, cover slips, safety goggles or safety glasses, a single edged razor blade or other sharp tool, pipette or dropper, water, a cork stopper, an onion, forceps or tweezers, an iodine solution, and paper towels.

Directions:1. To begin you will cut a thin slice off of the cork. It is absolutely necessary to USE EXTREME CAUTION when slicing the cork. Before you begin to cut the cork, put on safety goggles or safety glasses. Place the stopper on a cutting board and hold one end tightly. Be sure to keep your fi ngers well away from the end of the cork that you are cutting. Your slice must be thin enough for light to pass through it.

must use a microscope. The British scientist Robert Hooke was the fi rst person to describe the appearance of cells under a microscope. He looked at a very thin slice of cork- which comes from the dead outer bark of the cork oak tree. In this activity you will use a microscope to observe cork cells just as Hooke did, as well as to look closely at the structure of living cells from the skin of an onion.

2. Use the paper-thin cork slice to prepare a wet mount. Drop one drop of water on a clean slide and place the cork on top of it. Add another small drop of water on top of the cork, then gently slide a cover slip into place over the top.

3. Using the low power objective on your microscope, look at the thinnest area of the cork which is probably near the edge of the specimen. Be sure to adjust the diaphragm for the best contrast.

a) Draw the cork cells as you observe them under low power.

4. Now change to the high power objective on your microscope. b) Draw the cells as they appear under high power.

Label any cell parts that you recognize.

c) Describe the general shape and appearance of the cork cells.

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Cells Under the Microscope cont.5. Now you will examine onion cells. Begin by preparing a clean slide with a drop of water. Using a 1/2 centimeter square of onion, use the forceps to peel off a single layer of onion skin. Place the paper-thin piece of onion skin in the drop of water, and then add a cover slip.

6. Use the low power objective to look at the onion cells through the microscope. Don’t forget to adjust the diaphragm.

d) Draw the onion cells as they appear under low power.

7. Look at the onion skin under high power. Explore the effectof changing the focus very, very slowly using the fi ne adjustment knob.

e) What do you notice?

8. Stain is a useful tool that helps you to see the cell structures more clearly. Carefully add one drop of the iodine solution to the edge of the cover slip. Be careful not to get any stain on your clothing. Holding a small piece of paper towel with forceps, absorb some of the water on the opposite edge of the cover slip. As you absorb the water, the stain will be drawn under the cover slip. Look at the stained onion skin under low power, and then later under the high power objective.

f) Make a diagram of a single stained onion cell.

g) How does the stain change what you see?

h) Compare the cork cells and the onion cells. What differences did you observe? How were the cells similar?

i) How can you tell that the cork cells were nonliving?

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Vocabulary of The Microscope____ 1. gfaoaicimnitn ______________

____ 2. saeb ___________

____ 3. seln ___________

____ 4. jtebcvoei nlssee ______________ _____________

____ 5. mucpnood ghitl cspioomrce ______________ ___________ __________________

____ 6. cepsnioee _________________

____ 7. loteencr peimrooccs ___________ _________________

____ 8. srmoeopcic ________________

____ 9. etsoer ermscpiooc ___________ _____________

____ 10. efni saemntjtdu _________ _________________

a. A tool used in science to magnify tiny objects.

b. The type of microscope most often used in a classroom science lab.

c. The process of making an object appear larger than it actually is.

d. A highly advanced, specialized microscope that can enlarge objects more than 100,000 times their original size.

e. The part of a microscope that actually magnifi es an object.

f. The knob that allows you to focus the microscope when using high power objectives.

g. The bottom of a microscope, the part that rests on the table.

h. Lenses on a compound light microscope that are attached to the nosepiece.

i. The part of a microscope that holds the objective lenses. It is rotated to change the lenses.

j. A type of microscope used to look at details of larger objects such as rocks and fl owers.

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