1.31 Microscope Lesson

In this lesson, you’ll learn about the history and key parts of an essential scientific tool: the microscope. Microscopes have been around for centuries, but they continue to be updated, allowing us to see things we never thought possible.

What is a Microscope?

If you are wondering what exactly a microscope is, take a close look at the root word and its prefix. The root scope means to watch or see, and the prefix micro means extremely small. Together, you can see that a microscope is an instrument that allows someone to see very small objects. It can even let you examine things that you can’t see with the naked eye.

1. Main points:

The text explains the meaning of the word "microscope," breaking down its root and prefix to clarify that it’s an instrument used for viewing extremely small objects.

2. Questions:

– Content Analysis: What are the root and prefix of the word "microscope," and what do they mean?

– Linguistic Analysis: How does the text make the definition of ‘microscope’ easy to understand?

– Ideological Analysis: What does the text imply about the power of human observation with and without tools?

3. Further Discussion:

– Can you think of other tools that extend our human senses, like the microscope does for sight?

4. Answers:

– Content Analysis: The root "scope" means "to watch or see," and the prefix "micro" means "extremely small."

– Linguistic Analysis: The text breaks down the root and prefix of the word to make its meaning easy to understand.

– Ideological Analysis: The text implies that while the human eye has limitations, tools like the microscope allow us to "see very small objects" that we "can’t see with the naked eye."

History of the Microscope

There is no clear agreement on who first invented the microscope. Some say that Zacharias Janssen first invented the microscope in the 1590s. Zacharias and his father, Hans, were actually Dutch eyeglass makers. It’s believed that, together, they began experimenting with ways to use different lenses. When they put a lens at the end of a small tube, they discovered that objects near the end were magnified more than the lens by itself could achieve, and thus began their development of a microscope with multiple lenses.

Others believe that the true inventor was German-Dutch Hans Lippershey, also an eyeglass maker. He also created some of the earliest microscopes, and while he may have invented his own separately of Janssen, some argue that Lippershey actually stole designs for the microscope from Janssen.

An early compound microscope

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In the late 1600s and early 1700s, Dutch scientist Anton van Leeuwenhoek worked to create stronger lenses that vastly improved the microscope, allowing people to see incredibly small things. He was one of the first scientists able to observe bacteria, movement in water droplets, and blood in capillaries.

The microscope had many uses right away. One of the most significant uses is by British scientist Robert Hooke. In 1665, he published his microscopic observations in his book Micrographia. It was the first book to include illustrations of plants and animals seen through a microscope. With the magnifying powers of a microscope, Hooke was also the first to use the term ‘cell.’

1. Main points:

The text discusses the disputed origins of the microscope, its early inventors, and the significant advancements and applications in science.

2. Questions:

– Content Analysis: Who are some of the people credited with inventing or improving the microscope?

– Contextual Analysis: What time periods are mentioned regarding the invention and improvements of the microscope?

– Socio-cultural Analysis: Why do you think eyeglass makers were involved in the invention of the microscope?

3. Further Discussion:

– What other inventions can you think of that had unclear or disputed origins?

4. Answers:

– Content Analysis: Some of the people credited are "Zacharias Janssen," "Hans Lippershey," "Anton van Leeuwenhoek," and "Robert Hooke."

– Contextual Analysis: The time periods mentioned are the "1590s," "late 1600s and early 1700s," and "1665."

– Socio-cultural Analysis: The text mentions that "Zacharias and his father, Hans, were actually Dutch eyeglass makers," and Hans Lippershey was "also an eyeglass maker."

Parts of a Microscope

The most common type of microscope is the compound microscope, or a microscope that used two or more lenses. Most of these microscopes will have the same basic parts.

A typical compound microscope

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1. Eyepiece, where you put your eye to look into the microscope

2. Revolving nose piece, which allows you to switch between lenses

3. Lenses, contained in a tube that connects the lenses

4. Focus knob

5. Secondary focus knob, called a coarse adjustment knob

6. Fine adjustment knob, for further focusing after use of adjustment knob

7. Stage, the platform that holds the sample you’re looking at

8. Light source in the form of a mirror or light

9. Condenser, a lens that concentrates the light

10. Mechanical stage, a platform for the sample that’s movable

Types of Microscopes

Many scientists use basic compound microscopes on a regular basis to examine microscopic material. The most common type is the optical microscope, which focuses light to magnify an object. Usually, the maximum magnification for this type of microscope would be 1250x. In other words, an average optical microscope could make an object look 1250 times larger.

With the power of an electron microscope, you can see the jagged edges of sand particles.

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Electron microscopes are much more recent additions to the field of magnification. They look completely different from the compound microscopes you see in science classrooms. Instead of using light and lenses to magnify an object, they use electrons. Electrons have shorter wavelengths than light, which means they produce images that are sharper, and they can examine even smaller particles.

1. Main points:

The text outlines the parts of a compound microscope and distinguishes it from electron microscopes, which are a more recent development and use electrons for magnification.

2. Questions:

– Content Analysis: What are the main parts of a compound microscope mentioned in the text?

– Contextual Analysis: How are electron microscopes different from compound microscopes?

– Thematic Analysis: What types of microscopes are primarily discussed in the text?

3. Further Discussion:

– Can you think of any other tools that have undergone similar advancements like microscopes?

4. Answers:

– Content Analysis: The main parts of a compound microscope are "eyepiece," "revolving nose piece," "lenses," "focus knob," "secondary focus knob," "fine adjustment knob," "stage," "light source," "condenser," and "mechanical stage."

– Contextual Analysis: Electron microscopes are "more recent additions" and they use "electrons" instead of light and lenses to magnify objects.

– Thematic Analysis: The text primarily discusses "compound microscopes" and "electron microscopes."

Lesson Summary

Microscopes are important scientific tools that use lenses to magnify or enlarge very small items. With the magnifying power of a compound microscope, we can even see things that are invisible to the naked eye. Over the past few centuries, microscopes have become more and more advanced, even using electrons to clearly see the tiniest particles.