TOPIC: ATMOSPHERE
LEVEL: Beginner
"How Dry I Am"
[information |
preparation |
activity ]
- SCIENCE CONCEPT:
- The sun provides our planet with energy. The sun's heat energy makes the
water move, and causes water tp change form and evaporates into the air.
- STUDENT OBJECTIVE:
- The student will observe that water left in an open
container will disappear or evaporate into the atmosphere,
whereas water in a closed container will not evaporate.
- OVERVIEW:
- Students will compare and observe how water evaporates from a
paper towel that is left open in the air and a paper towel placed
in a plastic bag.
- TEACHER TEXT:
- A glass of water looks very calm left alone, but the
molecules are very busy moving faster and faster as the water
becomes heated. With sufficient heat the molecules break
their cohesive bond and escape into the atmosphere. This is
evaporation. On the other hand, when the water molecules touch
a cool object, they condense as water droplets on the glass.
Examples of this can be seen as dew on the grass, water forming
on a mirror after someone has taken a bath or shower, or
water condensing on the outside of a cool glass.
PREPARATION TIME: 30 minutes
LESSON TIME: 30 minutes
TEACHER PREP:
- Label paper towels with student names and use a string to
tie a clothesline across the room.
WORDS TO KNOW:
- evaporation
- evaporate
- condensation
- condensing
MATERIALS NEEDED:
PER GROUP:
- 2 paper towels
- 1 plastic bag with a "zipper lock" (gal size)
- 2 clothespins
PER CLASS:
- permanent marker
- string
- water
- STEPS TO FOLLOW:
- 1. Based on the activity "Now You See It, Now You Don't",
review what happened to the water paintings. Ask the question,
"Why did the water disappear?" Accept all answers and
explain that they are going to understand why the water disappeared.
- 2. Explain that people hang out their clothes to dry in the air so
the water can evaporate into the atmosphere.
- 3. Hold one piece of paper towel, wet, and another wet one in a
plastic bag. Based on their observations from the previous experiment,
have students predict which paper towel will dry first. Record all
responses.
- 4. Hand out the materials to the groups. Have each group carefully
wet their paper towels. Put one wet paper towel in a plastic bag with
a "zipper lock".
Take both paper towels and hang them on the clothes line.
- 5. Make periodic observation throughout the day.
- 6. Ask the students to look closely at the towel in the plastic bag.
- 7. Have students look closely inside the plastic bag. They should see
water present on the inside of the plastic bag. Ask the students where
the water came from.
- WHY?
- As water evaporates, it changes into a gas and escapes into the
atmosphere. The water in the plastic bag has no way to escape into the
atmosphere because it is trapped in the plastic bag. As the water is
heated in the plastic bag, the water builds up on the sides. This is
condensation.
- ASSESSMENT: Can the student communicate what they observed?
- 4....Student will be able to communicate that water evaporates into
the atmosphere as a gas. When water is cooled, it condenses and
appears as water like dew on the ground, water on a mirror after a
shower.
- 3....Student will be able to communicate that water will disappear
into the air and that the wet plastic bag will make water inside.
- 2....Student will communicate that the exposed to the air will
become dry and the towel in the plastic bag will become wetter.
- 1....Student will be able to communicate that it rained in the
plastic bag.