Download Lesson 1

Developed by CLACE- PI Marina La Grave, Dr. Barry Kluger-Bell and Kristine Johnson
UNIT: Water
LESSON # 1
TITLE: Evaporation
Summary: Children learn basic idea about
NASA Source:
Grade level:
Time:
Children
Learning
Outcomes:
evaporation and water vapor.
Adapted from the NASA sponsored,
Aquarius Education and Outreach
“Evaporation Investigation”
<http://aquarius.nasa.gov/pdfs/evap_inv
est.pdf>
3-5
Total time: 70 minutes
Snack & introduction: 15 minutes
Learning stations:
45 minutes
Summary and cleanup: 10 minutes
Children will learn that:
 Liquid water can turn to vapor, a gas,
in the air.
 How fast the water evaporates
depends on things like temperature,
surface exposed to the air, the amount
of water vapor already in the air
(humidity) and air movement.
Children will engage in and thereby
strengthen a number of scientific
practices such as:
 Design and carry out investigations on
what effects evaporation rate.
 Make claims based on evidence about
what effects evaporation rate.
 Communicate ideas about evaporation.
Children will be able to (cultural goals):
 Relate overall science learning goals to
the context of their schools, families,
and community.
 Communicate ideas, collaborate with
other children, and learn in a
personally meaningful way.
Big Questions:  Where does the water go when the
liquid disappears; for example, after it
1
Materials:
for evaporation activity
Item
Water sprayer
Electric fan
Desk lamp
with
incandescent
bulb
String and tape
to hang damp
paper towels
Item
Paper towel
Ziploc bag
Quantity
per group
of 12–15
1 per adult
1–2
1–2
1 roll each
Quantity
per pair or
trio
4
1
Take-home KIT per child:
Each child will receive:
1 small paintbrush
1 half sheet of paper with the
following instructions:
 Wet your paintbrush (under a
faucet or by dipping in a
container of water).
 Use your paintbrush to paint
different surfaces—a piece of
paper, a piece of newspaper,
the wall outside, the sidewalk.
 How do these surfaces look
when you paint them with
Developed by CLACE- PI Marina La Grave, Dr. Barry Kluger-Bell and Kristine Johnson
Lesson format:
National
Standards
Addressed:
forms puddles on the pavement or
when you put clothes in the dryer?
 What affects how fast water
evaporates?
Hands-on activity and discussion.
This activity relates to the following
standards from the Next Generation
Science Standards:
K-PS3-1. Make observations to
determine the effect of sunlight on
Earth’s surface.
K-ESS2-1. Use and share observations of
local weather conditions to describe
patterns over time.
2-PS1-1. Plan and conduct an
investigation to describe and classify
different kinds of materials by their
observable properties.
2-ESS2-3. Obtain information to identify
where water is found on Earth and that
it can be solid or liquid.
4-PS3-2. Make observations to provide
evidence that energy can be
transferred from place to place by
sound, light, heat, and electric currents.
5-PS1-1. Develop a model to describe
that matter is made of particles too
small to be seen.
5-ESS2-1. Develop a model using an
example to describe ways the
geosphere, biosphere, hydrosphere,
and/or atmosphere interact.
5-ESS2-2. Describe and graph the
amounts and percentages of water and
fresh water in various reservoirs to
provide evidence about the distribution
of water on Earth.
water?
 Watch your “paint” marks as
they disappear. What
happened? Can you relate it to
what we did today?
 Please remember to bring in a
show and tell object that
makes you think about water
or a drawing related to water
for next week.
Word Wall:
Include following words in
discussion (in both English and
Spanish), orally defined in
understandable terms, and
visibly displayed. If possible,
project a large image of the
words (and associated pictures)
on the wall of the teaching area.




Evaporation • Evaporación
Water vapor • Vapor de agua
Liquid water • Agua líquida
Transpiration • Transpiración
DIRECTIONS:
Overview: This session involves three parts and one take-home activity:
1) Start with a discussion about where they think water goes when things dry out.
2) Children then investigate things that might affect the rate of evaporation.
2
Developed by CLACE- PI Marina La Grave, Dr. Barry Kluger-Bell and Kristine Johnson
3) Children share their results and the facilitator discusses evaporation and
transpiration.
4) Instruction for Take-home Kit/activity.
Steps:
LESSON INTRODUCTION (15 minutes)


At the beginning of the session (during snack, if provided), show a multimedia
presentation to introduce today’s lesson.
o http://www.youtube.com/watch?v=k9l0s5zVibo
 Relate today’s topic to the last unit (air). Water is another component of the
earth system, and this unit will be all about water. Remind the children that by
learning about water, they will gain a better overall understanding of climate
change, because water is one of the important elements of our environment.
 Start with a question? Ask the children, “Where do you think the water goes when
puddles on the playground disappear?” Take all answers as you are trying to get
access to the thinking that children start with
o Ask the children to explain why they think that—what evidence do they have to
support their theories?
 Tell students that they today are going to be looking at something where two
components of the Earth’s system; air and water, combine. They will think about
clouds.
 Discussion question:
o Ask students what they think clouds are?
Be open to all ideas that they generate.
o Then tell them that today, they will hear what scientists have learned about
clouds and will be able to make their own cloud in a bottle.
o Show the first 2 minutes of the video
http://www.youtube.com/watch?v=HNjESP1CKSg&feature=related
 Follow with more questions:
o Where does the water go from the wet clothes you put in the dryer?
o Ask children to predict what will happen to the water if it is left out for a day
in an uncovered dish? Ask children what will happen if the dishes were
covered?
o Ask what they think might make the water disappear faster or slower?
o Ask the children to explain why they think that—what evidence do they have to
support their theories? If they have difficulty thinking of what might make
water disappear faster or slower, remind them of the dryer—does it have
different settings? Why? What do they do? Would water disappear faster from
a tall narrow drinking glass or a saucer? Why—what reasoning do they have
to support their theories?
Introduce the word evaporation. Tell the children that this process of water
“disappearing” into the air is called evaporation. Then tell them that today, they will
3
Developed by CLACE- PI Marina La Grave, Dr. Barry Kluger-Bell and Kristine Johnson
experiment to find out what makes water evaporate slower or faster.
LESSON LEARNING TASKS (40 minutes)
Procedures
Divide the children into groups of 2 or 3. [Have each group of children get two or more
paper towels.]
Discuss what they think will make paper towels dry faster, or slower.
Show them that you have:
 a place to hang towels,
 plastic bags to put towels in,
 a sunny spot or hot light bulb, and
 a fan.
 They should also try crumpling/wadding/folding the damp paper up vs.
laying it out flat.
Have each group pick one thing to change so that they can test how that one thing
effects how fast water evaporates. For example, they can choose to place one wet
towel in the sun, hang it, wad it up, put it in a plastic bag or put it in front of the fan.
Try to have at least one group examining air movement (the fan), surface area
(wadding), heat (sun/light bulb), and humidity (the bag).
Place the second towel on the table in front of them.
The facilitator will lightly mist all of the paper towels with about the same amount
of water using the sprayer. (Count the number of sprays and be consistent between
towels.)
Have each group of children observe and record what happens to the water. Which
towel dries fastest?
While waiting for their towels to dry, they can look at what other groups are trying
and/or record predictions and observations in their journals. If there is time and
the group is organized enough, they can test another variable.
Discuss what is going on here. See the background information above and below,
and move into the discussion and summary.
 Which towel(s) dried faster?
 Which dried the slowest?
 Can you rank them from fastest drying to slowest drying?
 Based on your observations, what conditions do you think increase or
decrease the rate of drying—the rate of evaporation? Why? Give evidence
for your ideas.
LESSON DISCUSSION AND SUMMARY (15 minutes)
After the activity, work with the children to summarize their results. Asking the questions
4
Developed by CLACE- PI Marina La Grave, Dr. Barry Kluger-Bell and Kristine Johnson
below, have children talk with their partner about their answers. Then have them share
their answers with the whole group.
Have the group discuss the results after the pair discussion.
 What things made the water evaporate faster?
 What things made the water evaporate more slowly? Explain to the children that the process of water evaporation is actually water "going" into
the air. The liquid water turns into water vapor (an invisible gas like air). Ask children for
some other examples of evaporation (for example, clothes drying when they are wet or the
water in a pail or glass disappearing when it is left out for a period of time. Discuss what is
happening with the water—which treatments “speed up” the water and help it leave the
surface of the towel? Which slow it down?
Discuss where evaporation takes place in the water cycle. When there is water on the
ground or in lakes or streams or in the ocean, some of it evaporates. Water from parts of
plants can also turn into water vapor in the air directly in a process called transpiration.
The water vapor in the air can eventually make clouds.
From this lesson, children should have learned:
 Liquid water can evaporate and become water vapor in the air.
 A variety of things can affect the rate of evaporation.
TAKE HOME
Children will take home a half sheet of paper with suggested discussion questions to ask
family and friends (in both English and Spanish). Introduce the Take-home activity with a
short discussion on “Where do you see evaporation happening in or around your home?
Where does water disappear or where do wet things dry out?”
Children will receive a small paintbrush and a half sheet of paper with the following
instructions:
 Wet your paintbrush (under a faucet or by dipping in a container of water).
 Use your paintbrush to paint different surfaces—a piece of paper, a piece of
newspaper, the wall outside, the sidewalk.
 How do these surfaces look when you paint them with water?
 Watch your “paint” marks as they disappear. What happened? Can you relate it to
what we did today?
 Please remember to bring in a show and tell object that makes you think about
water or a drawing related to water for next week.
ASSESSMENT:
 Ongoing, through the discussion and activities: monitor children’s usage and
understanding of words and ideas related to today’s lesson. Ask supporting questions
to encourage children to make connections. Clarify misconceptions.
5
Developed by CLACE- PI Marina La Grave, Dr. Barry Kluger-Bell and Kristine Johnson



Demonstrations of understanding: do any drawings, writing, theater, etc., display
sophisticated, accurate understanding of today’s lesson? Were children able to make
personal connections to the ideas? Were children able to make connections to prior
lessons?
Take- home work (assessed following week): did children follow through and discuss
the lesson with their families, bring a related show and tell object, and/or make a
drawing/other art project related to today’s lesson? Did discussion around these things
show continuing understanding of the ideas, including making connections to prior
lessons and to community?
Do children’s understandings, as displayed by their demonstrations of understanding,
questions, and discussion show connections between today’s topic, and the big picture
of the unit topic?
RELATED NASA ACTIVITIES AND RESOURCES:
NASA SCIENCE - Earth: Water Cycle
http://science.nasa.gov/earth-science/oceanography/ocean-earth-system/ocean-watercycle/
This site discusses the water cycle with particular emphasis on the oceans role in the water
cycle and NASA study of that process.
Earth Observatory: A Multi-Phased Journey
http://earthobservatory.nasa.gov/Features/Water/page2.php
This Earth Observatory site discusses the water cycle (hydrologic cycle) providing good
background information for facilitators.
Earth Observatory: Will runaway water warm the world? It’s not the Heat, it’s the Humidity
http://earthobservatory.nasa.gov/Features/WaterVapor/water_vapor3.php
This site explains the concept of relative humidity.
Global climate change - interactives: The Water Cycle
http://climate.nasa.gov/h2oWaterCycle/index.cfm
This site presents a very nice interactive graphic describing the water cycle.
BACKGROUND INFORMATION:
Evaporation is the process of liquid water leaving through the surface of the liquid and
becoming a gas in the air. This gaseous phase of water is called water vapor. On the Earth,
water is constantly evaporating and entering the atmosphere.
Evaporation is critical to driving weather and climate. It is a primary means for transferring
heat within the weather cycle. The sun powers the weather cycle. Fully 25% of the sun’s
energy received at the Earth’s surface goes into evaporation. Water entering the air as
vapor provides the energy that drives the water cycle. The water vapor in the air is also a
major natural greenhouse gas that helps keep our planet warm. Water is transported from
place to place primarily by wind, moving air, causing vapor and clouds in the atmosphere
6
Developed by CLACE- PI Marina La Grave, Dr. Barry Kluger-Bell and Kristine Johnson
to move. A huge amount of water is moved every day. An average of 3 mm (1/8 inch) of
water is evaporated over the entire surface of the Earth every day. This amount is higher in
the tropics and over the oceans, lower in the arctic and antarctic regions and almost zero
over deserts.
To understand evaporation, you have to think about water at the molecular level. In liquid
water, molecular forces hold the molecules together but they are all moving around at a
range of speeds. In cold water, the average speed is lower and in warm water, the average
speed is higher. Some of the molecules are moving fast enough to break through the
surface, escaping the forces that hold the liquid together, and moving into the air. These
escaping molecules carry away energy from the liquid. Since the fastest molecules are the
ones that escape, the average speed of molecules in the liquid decreases. The temperature
of the liquid then decreased, since temperature depends on the average speed of the
molecules.
The rate at which water evaporates depends on a number of factors. As mentioned above,
higher temperatures mean that liquid water molecules are moving at a higher average
speed. This means more molecules are moving fast enough to escape so the rate of
evaporation increases with water temperature. But molecules need a surface between the
air and liquid water to escape through. If that surface is small, few molecules will escape.
But as the water is spread out and the surface in contact with the air increases, there is
more surface to escape from and the rate of evaporation increases. Another factor that
influences evaporation rate is the amount of water vapor already in the air or relative
humidity. In addition to water molecules passing from liquid to air across the surface, there
are also water molecules from the vapor in the air passing back into the liquid. The higher
the humidity, the more water molecules are in the air so there are more passing back into
the liquid. High humidity will lower the overall rate of evaporation. Finally, if the air near
the surface of the water is not moving, escaped water molecules will build up in the air near
the surface, increasing the humidity near the surface and lowering the rate of evaporation.
However wind or other air motion can bring fresh, drier air near the surface and increase
the rate of evaporation.
As mentioned above, moving water from liquid into the air as vapor requires energy and
removes the fastest molecules from the liquid. This lowers the average energy per molecule
and hence, lowers the temperature. This process is called evaporative cooling and is why
sweat, evaporating from our skin, can cool us off. On the Earth’s surface, energy for rewarming the cooled water comes from the Earth’s surface, which is heated by the sun.
Evaporative cooling and convection (hot air rising and cool air filling its place) keeps the
Earth’s surface from overheating. The water vapor in the air is carried upward by
convection, condenses to form clouds, and precipitates down as rain, snow or hail. Energy
absorbed from sunlight is carried away from the surface in water vapor and released to the
atmosphere when vapor condenses into clouds. This transport of heat energy powers the
weather systems on the Earth.
CULTURAL BACKGROUND INFORMATION:
7
Developed by CLACE- PI Marina La Grave, Dr. Barry Kluger-Bell and Kristine Johnson
Water is one of the natural resources present in all aspects of human civilization.
Historically, the need and demand for water has been one of the driving forces for social
organization, economic prosperity, culture, development and health.
Then and now, the efficient use of this resource largely determines how one perceives,
assesses and manages it. Its effective use represents individual and collective well-being of
communities.
Historically, communities of the world honored and worshiped this important natural
resource. In its unique way, they created stories, gods, symbolisms and characters that
highlighted its importance:








To most Native American tribes, water was used as a clan symbol. To the Hopi,
Navajo, and Pueblo tribes the water clan named is Piikyasngyam.
To Peruvians, the god of water was Naylamp. It was believed that Naylamp came
from the sea, and brought civilization to the lands of Lambayeque.
To Hindus, Ganga was the goddess of the Ganges river and is represented ridding a
sea monster.
In Norse mythology, Ægir is the king of the sea, and is a personificates of the power
of the ocean.
To Greeks, Neptune governed all waters and seas.
To Mayas, Tlaloc (sometimes called Nuhualpilli) was the Nahuatl name of the God of
water and fertility in Teotihuacan and Nahuatl religions.
For the Egyptians, Sobek - was the water God. They believed that the Nile water
came from the sweat of Sobek and he was the god of all surface water.
To Japanese, Kappa is a mythological creature that lives in lakes, rivers and
wetlands.
The list goes on! Make sure to encourage your students to do a little research on a culture
of their choosing.
LESSON CONNECTIONS
This lesson is tied to ideas in other lessons:
In Lesson 2 (Condensation and the Water Cycle), children learn some basic ideas about
condensation and how water vapor changes to liquid water. This is followed by using this
understanding of condensation and what children learned about evaporation in the last
session to introduce the water cycle.
In Lesson 3 (Clouds), children gain some basic ideas about what clouds are and how they
form, drawing from what they learned in the previous two lessons (on evaporation and
8
Developed by CLACE- PI Marina La Grave, Dr. Barry Kluger-Bell and Kristine Johnson
condensation). The lesson starts with everyone watching the first 2 minutes of a NASA
video on clouds. Then each group does an experiment, assisted by the facilitator, where
they make a cloud in a bottle.
In Lesson 4 (Water and Life) children answer the question, “Why do living things need
water?” It has two active parts and a discussion. Children start with looking at how plants
take up water by doing the classical celery in colored water activity. This will require
saving materials to view in the next session. Next, children do a simple activity to get across
the idea that many chemical reactions (particularly biochemistry) need water to happen.
In Lesson 5 (Precipitation, Collection, and the Water Cycle), children delve deeper into the
water cycle in a three-part experience. The first part is a demonstration/observation
activity that models precipitation. The second is a discussion of what happens to the water
after it hits the ground. In the third part, children build closed system terrariums that show
the whole water cycle in miniature.
9