The compound microscope is believed to have been invented around 1595 by Zacharias Janssen and his father Hans Janssen. Their primitive device had two lenses that only allowed them to see objects about nine times larger than normal. The invention, however, quickly underwent many changes as other scientists altered the initial design. By 1665 some microscopes were able to magnify up to 250 times, a significant improvement over the capabilities of the early Janssen instrument.

Required Materials

• Science notebook
• Slide
• Glass marking wax pencil
• Dropper
• Small container of water
• Magnifying glass
• Ultrascope
• Source of light (flashlight or good room light)
• Newsprint and comics from the newspaper

Activity Directions

1. Draw a circle in the center of the slide with the glass marking wax pencil. The circle should be a little smaller than the diameter of a dime.

2. Add one drop of water to the circle and observe a lower case "e" in a piece of newspaper by looking through the drop. Draw what you in your science notebook.

   Is the "e" upside down or right side up?

   Is the "e" larger or smaller than the printed "e"?

3. Add two drops of water to the circle, observe the "e" again and draw what you see.

4. Add three drops of water to the circle, observe the "e" again and draw what you see.

5. Now start over with a one-drop microscope and observe a piece of colored paper from the comics. Explain what you see.

6. Observe the colored paper again using a two drop and a three drop microscope. Draw what you see in your science notebook.

7. Look at the newspaper "e" and the colored picture from the comics with the magnifying lens.

   How is the image similar and how is it different from what you saw using the water drop microscope?

8. Now use the Ultrascope to view the newsprint and the colored paper from the comics. If the paper is too thick for light to pass through it from the mirror, then have a partner shine the flashlight down on the slide so that the paper is well lighted.

   How is what you see different from what you observed with the other two types of microscopes?

   Is the letter "e" right side up or upside down?

   What are the three colors of the dots that make up the comics?

   Which of the microscopes produced the largest image?

9. The power of a microscope is described with a number followed by the letter "x." For example, if through a microscope you can see something 25 times larger than actual size, its magnification power is 25x. With most microscopes you can change lenses to increase or decrease magnification power. Click on the link below to see what various things look like through a microscope at different magnifications.

	Interactive Java Tutorial
Microscope Magnification Explore what various things look like through a microscope at different magnifications.

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