Title: Making Rain
(Note: This is a one day lesson designed for Mrs. Carral’s 2nd Grade Bilingual class at Grant Elementary School, Trenton, NJ.)

Observation or Question which initiated this Investigation:
This lesson serves as a follow up to a discussion on the topic of solids, liquids, and gases.  Since students are learning that a solid can change to the form of a liquid (and vice versa) and a liquid can change to the form of a gas (and vice versa), we want the students to witness the process of a change of state to further enhance their understanding on this topic.

Goal for Students:
The students will describe and explain in simple terms the change of state of the water.  The students will predict what the outcome of the experiment will be.  The students will also illustrate in their science journal the different stages of the water during the experiment.

Technique for introducing the Investigation for the students:
We will ask the question: Is it possible for it to rain inside a room?  Hopefully, this will generate a discussion that will make the students interested in pursuing the answer to our question.

Rationale behind using this particular approach to launch students:
In taking part of this experiment, the students will enhance their prediction skills.  The students will also become aware of the process of rainfall on Earth.  This experiment is also part of a unit of study on solids, liquids, and gases.

Basic Observations you have made regarding this Investigation:

List several Questions which could be addressed by this Investigation:

Materials needed:
Glass jar with very warm water,
Disposable aluminum pie pan with cold water and ice,
Newspapers,
Science notebook

Working Hypothesis:
It is possible to make rain indoors by heating water and cooling the water vapor.

Methods used in determining the validity of your Hypothesis:
    First, lay the newspapers down on a table in front of the classroom.  Heat the water in a clear jar using the microwave in the teachers’ lounge until it becomes very warm.  Place the jar on top of the newspapers.  Ask the students to describe what is happening to the water in the jar.  The students should understand that the water in the jar is evaporating and turning into a gas called water vapor.  If they do not, go back and review key terminology.
    Place cold water and ice in the pie pan.  Ask students what is happening to the ice on the pie pan.  Students should understand that the ice is melting and turning into the form of a liquid.  Again, if students do not, go back and review key terms.
    Ask the students to predict what they think will happen to the water vapor once the pie pan is over the jar.  Write their predictions on the board.  Next, place the pie pan over the jar.  Wait and see what happens.  The cold surface of the upper pie pan cools the water vapor from the jar.  The water vapor changes back into water, collecting in drops.  As the drops get bigger and heavier, it “rains.”
    Once it “rains,” tell the students that this experiments explains why it rains outside.  The warm water in the jar is like the water in lakes, rivers, oceans, etc. on Earth that are heated by the Sun.  As the vapor rises from the water, it is cooled by the air.  You may even see clouds (which look like steam) when the droplets begin to form.  As these droplets collect more moisture, they become heavy enough to fall to earth as rain.
    After this discussion, the students will be asked to take out their science journals and explain the process of how a gas changes into a liquid.  Then, the students will be asked to illustrate and label the different stages of the process that they saw.  Next, the students will turn to the person sitting next to them and answer the question “How did the water in the jar change?”

Variables which need to be controlled:

How will you record your Results? (List at least two ways to produce data in a form which can be discussed and analyzed.)
We will write the students’ predictions on the board.  Also, in their science journals, the students will illustrate and label the different stages of the process they witnessed.

Show your Results:

Possible student predictions that may be written on the board:
-the heat from the jar will cause the ice in the pie pan to melt
-nothing will happen
-condensation will occur
-the pie pan will warp and melt due to the heat from the jar
-the water in the jar will become cold
 

Was your Hypothesis supported, or not?
How can you tell?
Yes, our hypothesis was supported because we succeeded in making rain indoors.  In other words, the results failed to disprove the working hypothesis.

(Analysis) Discuss what your Data means:
The students will have a more concrete idea of how a solid can change into a liquid (and vice versa) and how a liquid can turn into a gas (and vice versa).  In addition, they will have a clearer understanding of how and why rainfall occurs on Earth.

What would be some follow-up Questions which were not resolved by your experimentation?
How would the process differ if you used a different material or substance other than water?

What improvements would you make in your Experimental Design?
One improvement we would make is to add an additional step to the experiment.  We would place cold water in the jar instead of warm water and repeat the experiment.  We would then have students predict if the same outcome will occur.  We can assess their understanding by seeing if they realized that it is the heat from the warm water in the jar that is a necessary variable to make this experiment work.


Citations:
Badders, William, et al.  Science Discovery Works.  Boston: Houghton Mifflin, 2000.

Mandell, Muriel.  Simple Weather Experiments with Everyday Materials.  New York: Sterling Publishing Co., Inc.