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Evidence-Based Guesses

What is the connection?

Goal:

Goal:

When you read scientific articles, you may have to figure out how two concepts are related. That's because the relationship between concepts may not be directly stated. It may be suggested, and the writer may expect you to infer the connection. Do you remember what inferences are? Inferences are guesses that are based on given evidence. 

Click the Read Me button to read an article that describes how scientists first learned about decompression sickness (DCS). When you are finished reading, answer the questions below. Click the options that correctly answer the questions. Click the Next button to move to the next question.

How are Robert Boyle's experiments related to the sickness experienced by bridge builders many years later?

  1. Robert Boyle performed experiments on bridge builders as well as on snakes in bell jars.
  2. Robert Boyle used to be a bridge builder before he became a scientist.
  3. What happened in the snake's eye also happened in the bridge builders' bloodstreams.

No, Robert died many years before the bridge builders were born, so he couldn't perform experiments on them.

The article does not say what else Robert Boyle did besides science experiments.

Yes! The same concept applies to both a snake's eye under pressure and bridge builders' blood under pressure. There is liquid in both an eye and in blood, and bubbles of air can form in each under pressure.

According to the scientist who figured out how to avoid decompression sickness, how are time and pressure related?

  1. Time and pressure can be used to prevent gas bubbles from forming deep under water.
  2. The more time you take to release pressure on a liquid, the fewer gas bubbles form inside the liquid.
  3. The faster you create pressure on a liquid, the slower the gasses in the liquid can move around.

No, pressure actually causes gas bubbles to form deep under water.

Right. Bert figured out that bridge builders were moving from high pressure to low pressure much too quickly.

Releasing pressure more quickly actually causes gasses to form larger bubbles, not move more slowly.

What does bridge building have to do with scuba diving?

  1. Both activities involve placing people deep under water, where the pressure on objects is higher than at the surface.
  2. Both activities require people to wear wet suits and carry oxygen tanks in order to survive.
  3. Both activities can be done without training if someone can hold his or her breath long enough.

Yes, diving and bridge building can lead to decompression sickness when people go deep under water.

No, the bridge builders in the article did not wear wet suits or oxygen tanks--they stood in an air-filled room inside the caisson.

Both activities require much training. Otherwise, they can lead to severe illness or death.

Summary

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