Body : Start some water boiling in a hot pot for use in section 2.
1. Students can sit at their desks while they do this section of the lesson. Pass out two sheets of shiny paper, a cup of water and a set of water colors to each student. First have the students get their brushes soaking wet and dip their brushes into the yellow paint. Have the students make many large yellow drops all over one sheet of the shiny paper. Rinse the brushes and make many large blue drops between the yellow drops being careful not to mix the drops. With a second sheet of shiny paper covering the desk, have the students lift their paper so that it is perpendicular to the desk and the drops start to run down the paper. The drops should slide down the paper and mix with each other dripping off the bottom of the paper as large green drops. Ask: "What happened to the blue and yellow drops when you lifted your paper? What happened to the paper flat on your desk? Is there a new color on your papers? What is the color? How did the new color get there? Were the drops which fell off the bottom of your paper the same size as the blue and yellow drops?"
2. The class should gather around a common work place where they can all view the hot pot and bowl of ice. Explain to the class that you are going to hold the pot of ice water over the boiling water. Ask: "What do you think will happen - to the bowl of ice? to the steam? to the bottom of the bowl?" Once the water is boiling, hold the bowl of ice over the steam. Place a pie tin so that the water which drips from the bottom of the bowl will collect in the tin.
The class should observe and share what they observe happening. Some questions to help: "What do you see happening on the bottom of the bowl? What do you see happening in the pie tin? How does the water get on the bowl? Are the water drops on the side of the bowl the same size? Why? Which drops are falling from the bowl? Why? Which drops look like rain? Which drops look like a cloud? How are the big drops formed?"
Explain that the small misty drops which have condensed onto the side of the bowl of ice represent a cloud. The winds in a cloud blow the small drops around so that they collide with one another. During these collisions, some drops will combine with others making bigger and bigger drops. When the drops become so large that the winds cannot keep them in the sky, the drops fall as rain or precipitation. This is similar to the large drops falling from the bottom of the bowl.
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