Lesson 1: Convection’s role in creating wind

Activity 1. Pie pan convection

In this lesson students will investigate the connection between the heat, density, the movement of a fluid (air) and how this creates convection through two activities. The lesson concludes with a discussion of larger scale convection currents and wind.

Online Resource:

• http://www.teachingboxes.org/catalog.jsp?id=DLESE-000-000-007-913

Materials:

• A copy of the instructions for each team of students: http://www.teachingboxes.org/catalog.jsp?id=DLESE-000-000-007-913
• Aluminum pie-pan
• Hot plate
• Dye or food coloring: any color will do
• Tap water
• Bottle of liquid hand soap or shampoo that has a pearly or metallic appearance. Look for the following ingredient on the label: glycol stearate, glycol distearate or glycerol stearate. Good brands to try are Softsoap® and Walgreen's Liquid Soap.

Advance Preparation: Read through the procedure for the experiment; gather the materials needed for the students

Time needed: Teacher preparation: 20 minutes; Student activity: 30 minutes

Procedure:

Students will create convection cells using soapy water, food coloring, and a heat source using this resource: http://www.teachingboxes.org/catalog.jsp?id=DLESE-000-000-007-913.

1. To introduce the concept of convection, ask students to imagine that they are in the kitchen. They take out a pot and fill it half way with water. They put it on the stove and turn the stove onto high. What happens to the water? Why? (The water will boil.)
2. Explain that the water at the bottom of the pot heats up first. This causes it to expand. Since the warmed water has a lower density than the water around it, it rises up through the cooler, dense water. When the water reaches the top of the pot, it cools and increases in density, which causes it to sink back down to the bottom. This rising and sinking movement (cycling) is a convection current.
3. Divide students into teams of two.
4. Provide each team with a set of instructions and materials.
5. Have the students follow the instructions under “Assembly” and “To Do” .
6. When the students are finished, have them describe the movement of the soapy water as it heated.

Closing the activity: Discuss with the class how the soapy water moved throughout the experiment. As the solution heated up, it became less dense and rose to the top in columns. The warm liquid cooled and sunk to the bottom. The regions where the fluid rises and sinks are convection cells.

Lesson Vocabulary: Convection, current, density, temperature, fluid