Focus Question: Where does

the water go when something dries?

Investigation 3 - 1

Wet and Dry

When it rains and the pavement gets wet, who dries it?

We’re going to do an investigation to find out where the water goes.

Investigation Set-up

Place both paper towels in the water.

Squeeze out most of the water and place one towel in each cup.

Place cups on balance and add drops of water to lighter cup until they balance.

Paper towels get wet when people use them to soak up spills. They can sometimes be used again if they are dried out. These two towels are equally wet.

Watch these for a day to see how fast they dry.

To make things a little more interesting, cover one cup with a lid. Place the second lid under the other cup so it still balances.

Sketch the investigation set-up in the Before box on your observation sheet.

Observations Sketch the investigation in the After box.

Take the paper towels out of the cups, compare them and describe the difference.

Discuss in your group: Which side of the balance went up and which

side went down?

What caused one cup to go up and one to go down?

What happened to the water on the two paper towels?

Evaporation The paper towel exposed to air dried out.

The water in the towel changed from liquid water to water vapor, an invisible gas.

Process by which liquid water changes to water vapor is called evaporation.

Water vapor in the open cup evaporated and escaped into the surrounding air.

Water in the closed cup was not able to escape into the air.

All the original water stayed in the closed cup.

When the water in the open cup evaporated, the paper towel got dry.

Water in the closed cup didn’t evaporate, so the paper towel stayed wet.

Wet paper towel is heavier, so that side of the balance goes down and the side with the dry paper towel goes up.

Record your explanations on the notebook sheet. Include what happened to the balance, the paper towels, and the water.

Vocabulary

Evaporation - The process by which a liquid, such as water, changes to a gas

Water Vapor - The gas state of water

Content What happens to a wet paper towel in an

open cup?

What happens to the water in a paper towel when it evaporates?

Your questions?

Homework: Read “Drying Up”, pages 182-183, take 3-column notes and answer questions.

Drying Up Questions What is water vapor?

Where is water vapor?

What does water vapor look like?

What happens when a wet object gets dry?