Seeing the Invisible

Which evidence supports the conclusion that early Romans were responsible for the invention of the microscope?

• They discovered that a piece of glass that was thick in the middle and thin at the edges could make objects appear larger.

• Lenses were not used much until the 1300s.

• They put several lenses in a tube and look through them at an object.

• During the 1800s, major improvements were made to the microscope.

Part A

What is the main idea of the passage?

• The invention of the microscope was an accident.

• The modern microscope is the result of many people’s efforts.

• The greater the curvature of a microscope lens, the more it magnifies an object.

• The invention of the microscope led to a scientist’s discovery of cells.

Part B

Which summary BEST supports the main idea from Part A?

• Lenses are named after the lentil bean. One scientist chose to grind and polish the lenses so they could magnify objects at a higher level. Then he used the lenses to make new discoveries from a drop of blood.

• There are two types of microscopes: compound and electron. Scientists have used these microscopes to observe insects, a cork, and pond scum. A book was written about discoveries one scientist made while using the microscope.

• The Romans found that glass could magnify objects. Then people started to wear lenses for vision. Two spectacle makers turned the lenses into a microscope. Scientists experimented with

  the lenses and made important discoveries. These scientists also improved the microscope over

  time.

• A microscope is used to look at objects that are difficult to see. The microscope uses a combination of lenses that have been improved over the years. The best lenses in the world were created by people who studied optic design.

Which statement BEST explains why this passage is nonfiction?

• The passage includes directions on how to make a microscope using different types of lenses.

• The author uses factual information about microscopes and presents this information in chronological order.

• The author tells stories about scientists from different time periods who worked with microscopes and made discoveries.

• The passage includes predictions about how future scientists will improve the microscope.

How does the illustration contribute to the passage?

• It directly supports information in paragraph 3 about how the microscope was used to study plants.

• It helps the reader locate definitions of microscope vocabulary used in the passage.

• It directly supports the description of a microscope in paragraph 6.

• It helps the reader understand how microscopes have improved over time.