Now You See It, Now You Don't
This lesson investigates the process of evaporation. Through video and
hands-on activities, students will better understand how and why molecular
movement is responsible for the evaporation of liquid. This is a two-part
lesson, with data collection taking place over at least a two-week period in
EUREKA! #18 "Evaporation and Condensation"
To get a copy of the video, please contact:
TV OntarioIT FIGURES #16 "Bar Graphs"
To get a copy of the video, please contact:
Agency for Instructional Technology
Students will be able to:
- Name the three states of matter
- Explain the difference in the movement of molecules found in the three
states of matter
- Demonstrate recognition of the fact that molecules are too small to see
unless millions are together
- Discuss and report on the process of liquid evaporation
- Record data on water evaporation occurring in different containers
- Identify the parts of a complete graph
- Interpret data from the experiment and apply it to a graph
- Formulate a conclusion based on data from a graph.
For each student:
For each group of 4 or 5 students:
- Eye dropper
- Small container of water (film canisters work well)
- Paper towel
For the class:
- Data Collection Sheet for graphing *
* Located at the end of the lesson.
- 1 long jump rope or several shorter ones tied together
- 4 or 5 clear containers of different sizes and/or different shapes
- Paper centimeter-rulers
- Food coloring
- Evaporate - to convert into vapor
- Gas - a fluid (as air) that has neither independent shape nor volume but tends to expand indefinitely
- Liquid - flowing freely like water
- Molecule - the smallest particle of a substance that retains all the properties of
the substance and is composed of one or more atoms
- Property - a quality or trait belonging, and especially peculiar, to an individual
- Solid - a substance that does not flow perceptibly under moderate stress
- State - a mode or condition of being.
If the students have some prior knowledge of the three states of matter, you
may be able to omit the following part of the lesson.
TEACHER: "Today we are going to learn about liquid and some of its
properties. First let's find out a little about the three different types of
matter." Place 1 or more jump ropes on the floor to form a circle about 5 or 6
feet in diameter. Ask for 8 volunteers and explain to them that they will
represent water molecules in the three different states of matter.
Instruct your volunteers they are to move back and forth inside of the rope
circle but that they cannot move their feet.
TEACHER: "Our circle represents
a drop of water. The people inside of the circle are molecules. What happens
when you put water in the freezer?" (It turns to ice.) "Think about an ice
cube, describe its shape." (A definite cube.) "Can you pour an ice cube like
water?" (No.) "Can you put your finger into it?" (No.) "Why not?" (Because
it is solid.) "Solid matter keeps its shape because the molecules are stuck in
place even though they are always moving. What happens to an ice cube
when you leave it in the sun?" (It melts.) "Why do you think this happens?"
(The molecules are no longer stuck in one place.)
TEACHER: "Let's pretend you are our ice cubes in the sun and see what heat
does to the molecules." Instruct your volunteers to move about inside the
circle. They need to move more quickly and move their feet around but must
stay inside of the circle. "What do you notice about our ice cube now?" (The
molecules are moving around faster.) "What is happening to its solid form?"
(It's losing form, melting.) "Right, our ice cube is now a puddle of water. How
is water different than ice?" (You can pour it, put your finger in it.) "What
made the molecules move faster?" (Sun, heat.)
TEACHER: "If you spilled some water on the sidewalk in July, what would
happen to it?" (It would dry up.) "What would it look like 2 hours after you
spilled it?" (It would be gone.) Instruct your volunteers to move about
quickly and when they bump into another molecule to leave the rope circle
and move about the classroom. You may want to give them a start signal this
time. "Now our puddle of water has been out in the sun for a while. Let's see
what happens to the molecules when they get even hotter." Teacher signals
to the volunteers. Within a few seconds, all of your molecules should have
left the circle and be moving around the classroom. "Now that the molecules
have left the puddle, where are they?" (In the room, moving around.) "How
many molecules are left in the puddle?" (None.) "That's right, they are now
moving around in the air and are called a gas." Ask your volunteers to
return to their seats.
TEACHER: "Turn to your neighbor; one of you tell the other how the
molecules move in a solid. Now, the other partner, tell how molecules
move in a liquid. First partner again, tell how molecules move in a gas.
Second partner, tell what the three types or states of matter are." Allow time
after each direction for the students to complete the task. OBJECTIVES 1 & 2.
Prepare a small container of water and an eyedropper for each child. Ask the
students to put one small drop of water on the back of their hand with the
eyedropper. Instruct them to observe the drop while they blow on it gently.
Allow a few minutes for them to do this. Ask the students to turn to their
neighbor and explain what happened. Ask several students to share what
they think happened, while the teacher places their responses on the
chalkboard or on a large piece of paper.
It is important to give students a specific responsibility while viewing.
Knowing what they are expected to learn allows them to focus on specific
information and concepts in the video.
TEACHER: "Listen for the reason
liquids do not have a definite shape. When you hear it, raise your hand."
PAUSE after the character flies out of the fish bowl. Check for understanding.
Students are to explain to their group or the whole class the similarities and
differences between the popcorn and the molecules in the video.
TEACHER: "Watch this next segment to discover whether or not you can see
molecules and why."
PAUSE after the narrator says, "when they make up the water in your
goldfish bowl," and there is a picture of a fish. Check for understanding. Ask
students to share with a neighbor when they can see molecules. OBJECTIVE
TEACHER: "Listen and be able to tell me what water is called when it is in
the air and what we call it when it changes from liquid to gas."
STOP after the narrator says, "evaporation." Check for understanding.
Students in their group discuss the nature of evaporation. Give the groups
time to reach an agreement on the definition. The groups report to the whole
class, and all record their definitions. Compare definitions to summarize
learning or main points. Develop a class definition. OBJECTIVE 4.
The teacher brings out 4 or 5 clear containers of different shapes and/or
different sizes. Make sure that they have different surface areas for the
water. Label the containers A, B, C, D, etc.
TEACHER: "Let's experiment with evaporation. If we put water into these
containers and leave them in the classroom in a quiet place, what do you
think will happen to the water? With your group, make a prediction about
the containers according to the following: fastest evaporation, next, next, and
the slowest. Write your predictions on your paper." Allow time for the
students to discuss the predictions and reach a group agreement. Post each
groups' predictions on butcher paper for later reference.
TEACHER: "A paper ruler will be taped to the side of each container, and it
will be filled with water." Color the water for easier reading.
TEACHER: "How will we keep track of how much water evaporates?"
Teacher or students will list suggestions and choose one that will work.
Note: A Sample Data Collection sheet is included at the end of this lesson.
The teacher could have groups collect their own data or assign a group or a
student to record the changes in each container for the whole class.
Students should collect data at least 3 times a week. After they have collected
data for at least 2 weeks, move on to PART 2 of the lesson. OBJECTIVE 5.
Video: IT FIGURES #16 "Bar Graphs"
TEACHER: "We are going to watch part of a video that will resemble a
favorite fairy tale. Listen to discover the queen's problem."
CUE video to the beginning of the "Queen of Hearts" cartoon and START.
PAUSE after the narrator says, "she's been running out of tarts long before the end of the week!" Check for understanding. Ask the students to name
the queen's problem. Discuss responses and make sure they understand the
TEACHER: "Predict how you think the queen will solve this problem. Tell
your prediction to your neighbor."
Note: Allow a minute for them to think and share. "Now let's listen to
what the queen chooses to do."
PAUSE after the queen says, "might give us a clue," and the king nods his
TEACHER: "Raise your hand if your prediction about the queen was
correct. From the next segment, be able to tell your neighbor what kind of
information is collected and what it looks like."
PAUSE after the queen says, "Isn't there a simpler way to show how many
tarts were eaten each day?" and the king runs off.
TEACHER: "What did the information look like? Was it easy to understand?
Can you think of a better way to show this information?" List some of their
suggestions on the chalkboard, or have them tell their neighbor. "Now listen
to what the king thinks is a better idea. Be ready to tell your group."
STOP after the queen says, "write down the same things for week 2 and week
3," and the king runs off. Teacher directs students to list on paper, or orally,
the parts of the graph that were missing. OBJECTIVE 6.
TEACHER: "Let's decide how we can use the information about graphs to
help us record our own data from our evaporation experiment." Students
design graphs in their group based on the data collected from the experiment.
When they are finished, bring them together in a large group
and have each group present their graphs. When all graphs have been
presented, try to reach a conclusion about which container had the most and
least evaporation and why. This conclusion should be checked against the
students' earlier predictions. OBJECTIVE 8.
Assessment: Check for student understanding of the graph results and the
concept of evaporation. Activities under Action Plan and Extensions are
suitable for assessment, also.
Invite a speaker from a water management company to reinforce and
expand on "molecules" and "evaporation."
Let students design experiments with evaporation from containers covered
with different materials such as cotton, nylon, or plastic and discuss how
these things might be useful and why. This activity may be used as
Students draw pictures on black or blue paper and "paint" over it with a
solution of 1/3 cup Epson salts dissolved in 1/2 cup water. When the water
evaporates, crystals will be left.
Does water evaporate from plants? Design "a discovery," or use the
1. Wet 2 paper towels equally, straighten one out, and leave one in a
crumpled ball. Check often to see which dries out first. Discuss the results.
2. Wet 2 paper towels equally, wrap one in wax paper, and leave one without.
Which dries faster? Relate this to the waxy skin of cacti and other desert
plants. Is water the only liquid that evaporates? Students hypothesize about
this matter and then design an experiment to determine this, and graph
results of the findings. They will need to validate their hypotheses and
summarize their findings.
3. Both of these activities in science may be used for assessment.
4. Other ITV courses from ASSET on the topic of evaporation:
- MAGIC SCHOOL BUS, Series 2, #6 "Wet All Over"
- SCIENCE IS ELEMENTARY #3 "Let's Explore Water"
- 3-2-1 CLASSROOM CONTACT #12 "Go with the Flow"
- VOYAGE OF THE MIMI #19 and #20 "Making Dew" and "Water, Water
Click here to view the
worksheet associated with this lesson.
Master Teacher: Ann Parra
Lesson Plan Database
Thirteen Ed Online