Teacher Portal:
Microscopic Exploration
Investigation 1 – PreLab
ASK WHY
Microscopes are one of the most important scientific instruments developed. In fact, in the medical field, microscopes are largely responsible for making modern medicine “modern”!
BRANCH OUT
Cell Biologists study how cells work. Cell Biologists are involved in important research in many different areas of biological sciences. They are employed at universities, hospitals, clinics, and industry.
PRINT IT
Use your browser to download a printable PDF as help during the slide presentation and to make additional notes. In your browser, go to File > Print and then choose to save as PDF.
MINDSET
This Investigation is designed to:
- provide you with an opportunity to view objects with the unassisted eye, a convex lens, a concave lens, and the compound microscope.
- allow you to investigate the differences and similarities of an object and the image of the object produced when using different lenses.
- encourage you to realize that the proportions of an object are the same regardless of whether an object or an image of the object is viewed.
- promote the understanding that lenses refract light and that the refraction of light produces an image that appears different from the object being viewed.
- introduce you to the compound microscope and its use.
- expand your understanding of refraction and resolution produced by lenses.
SCIENTIST’S GLOSSARY
- Convex lens: A curved lens that refracts light, bringing parallel rays of light to a point. Convex lenses are thicker in the middle than at their edges and can produce a magnified image of an object.
- Concave lens: A curved lens that refracts light, producing an image of an object that is reduced in size. Concave lenses are thinner in the middle than at their edges.
- Lens: A curved piece of transparent material, usually glass or plastic, that refracts light.
- Magnify: When the size of an object’s image is increased. Magnification often occurs because of the refraction of light.
- Microscope: A scientific tool that is used to view objects that are too small to see using the naked eye.
- Microscopy: The science of observing very small objects and details of the objects.
- Refract: When light passes through a transparent substance and is bent or redirected in a different direction.
- Resolution: The process that makes fine details more clearly visible.
BE PREPARED
Watch the Investigation 1 Teacher Video and Student Video below to prepare for the PreLab.
SET FOR SUCCESS
- Tell students that they are about to begin the Microscopic Explorations CELL.
- Ask students to share the kinds of things they expect they might learn in these Investigations.
- Tell students they will think about light, magnification, and plant and animal cells.
Begin the PreLab Concept Slides to start students on their learning journey. Then watch the Pre-Lab Student Video as a class.
NAVIGATE IT
Once the slide presentation is launched
- use your left and right arrows to advance or go back in the slide presentation, and
- hover your mouse over the left edge of the presentation to get a view of the thumbnails for all the slides so that you can quickly move anywhere in the presentation.
- Click HERE to launch the slide presentation for the CELL.
SHARE IT
SLIDE MICRO1-pre-1
In this Investigation, we begin our study of the incredible world of cells. Cells are so small we cannot see them with our naked eyes. We must use a microscope to see them. You will learn a lot about cells in LabLearner, both in this CELL and in your middle school years.
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SLIDE MICRO1-pre-2
In Investigation 1 we will discuss how lenses work by refracting (bending) light.
In later Investigations, we will learn to use a compound microscope to study both plant and animal cells.
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SLIDE MICRO1-pre-3
Before learning how a microscope magnifies images of plant and animal cells, we first have to understand a little about how lenses work and magnify images.
Read the slide as a class and discuss the illustration of light passing through a glass of water.
What is the definition of refraction? Refraction is the bending or redirection of light as it passes through transparent substances.
What is the term scientists use to describe a substance through which light travels? Scientists use the term medium to describe substances through which light travels. Media is the plural of medium.
Why is light refracted as it travels from one transparent medium to another medium? Light is refracted as it travels from one transparent medium to another because light travels at different speeds in different media. The change in the speed of light, either slowing down or speeding up, causes the light waves to bend or refract.
Would refraction of light occur if light traveled from one area of air to another? Why? No. Refraction occurs when light travels from one medium to a different medium because of a change in the speed of light in the two different media. In the question above, the air in both areas is likely exactly the same, and therefore light would travel at the same speed in both areas. Therefore light would not be refracted.
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SLIDE MICRO1-pre-4
Read the slide as a class and think about the following questions.
Scientists give a special name to what a person sees when light is refracted. What is this term? An image of an object is produced by the refraction of light.
What is the difference between an object and its image? An image is what someone sees as a result of the refraction of light. It is not “real” in that it cannot be touched or handled. The term “object” describes a “real,” tangible material or substance that is viewed.
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SLIDE MICRO1-pre-5
Continue reading this slide as a class and discuss the following questions:
Does refraction of light always produce an image that looks different from the object? No. Sometimes the image produced looks very similar to the object.
What types of materials can produce images that look different from an object? Lenses often produce images that appear very different than the object.
What types of materials can produce images that look different from an object? Lenses often produce images that appear very different than the object.
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SLIDE MICRO1-pre-6
This slide introduces the two most common lenses that students will encounter. The convex lens bulges out in the middle on both sides of the lens. The concave lens, on the other hand, dips in on both sides of the lens. Students will use and explore the properties of both types of lenses in Investigation 1 Lab.
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SLIDE MICRO1-pre-7
Finish the discussion of what students learned from reading the passage by asking them to think of five important points they learned from the passage. Suggest that each point be described in one sentence. Students may record these five points in problem #1 in their SDRs.
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SLIDE MICRO1-pre-8
Which Image Set showed changes in the resolution of the images? Why? Students should indicate that changes in the resolution of the images can be seen in Image Set B. In Image Set A, the images increase in magnification from Image A1 to Image A3. However, no additional detail can be seen in Images A2 or A3 as compared to Image A1. In Image Set B, the images also increase in magnification. In addition, increasing amounts of detail can be seen in Image B3 as compared to Image B2 and B1. Individual streets can be seen in Image B3, but not in Image B2 or B1.
Ask students: What other changes in the images in each set did you observe? How are these changes different from changes in resolution? Student answers will vary but should indicate that the images in both Image Sets increased in magnification from A1 to A3 and from B1 to B3. As a result of the magnification, parts of the images appear larger. However, in Image Set A, the increase in magnification did not result in the ability to discern additional details of the image. In contrast, the increase in the magnification in Image Set B resulted in the ability to see more detail of each image. That is, the magnification was accompanied by increased resolution of the images.
Do you think there is a relationship between the refraction of light and the ability to change the resolution of images? Student answers will vary. Tell students that this question is one that they will investigate during their experiments in the lab.
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SLIDE MICRO1-pre-9
By performing your lab experiments, you will begin to answer the following questions:
• What is the result of the refraction of light by lenses?
• How do lenses affect the resolution of the images of an object?
PRELAB EXERCISE
1. Think about the passage you read. What do you think are five important facts someone should know about refraction? Write the facts in your SDR on page 3.
2. Look at Image Set A and Image Set B. Think about what the term resolution means. Discuss it with your partner or class and answer the question in your SDR on page 3.
3. In which set do you see changes in the resolution of the images? Explain your answer in your SDR on page 4.
KEYS: PRELAB EXERCISE
WATCH IT
Play the following Student Video in preparation for the lab. Discuss as necessary to answer student questions.