Lesson 1: Convection’s role in creating wind

Activity 2. Currents in water

Online Resources:

• Teacher's guide: http://www.teachingboxes.org/catalog.jsp?id=DLESE-000-000-005-588 This activity is part of a larger activity entitled “Atmospheric Processes - Convection.”
• Student guide: http://www.ucar.edu/learn/1_1_2_7s.htm This activity is Part 1 of the student guide.
• Currents in water Student Worksheet

Materials:
For the class:

• Pitchers or jugs for water
• A source of very hot water, such as an electric teakettle, hot plate and regular kettle, or coffee maker (hot tap water is usually not hot enough)

For each team of students:

• Clear plastic plant saucer 8 to 10 inches wide. Caution: DO NOT use saucers with concentric raised rings on the inside bottom; radial ridges are okay
• Pitchers or jugs for hot and cold water
• Food coloring
• Small container for food coloring (a small cup would work fine)
• Medicine dropper or pipette
• Four Styrofoam cups
• Dump buckets

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

Time needed: Teacher instructions - 15 minutes; Student activity - 30 minutes

Procedure:

Working in groups of 4, students will conduct various experiments to trace currents when water is not heated evenly. In the first experiment, they will observe the movement of a drop of food coloring in still water. Then they will conduct variations to the experiment in which they have a heat source and add food coloring to the set-up in various locations. Students will be asked to observe (draw) and record what happens to the drop as it sits in the tray. At the end, students should be able to describe the effect that hot water under the center of the saucepan has upon currents. They should also be able to describe the heat transfer that is taking place (convection).

1. Review the teacher guide: http://www.teachingboxes.org/catalog.jsp?id=DLESE-000-000-005-588 before class. Students will perform the experiment and the variations in Part 1
2. Print out the student guide for each student: http://www.ucar.edu/learn/1_1_2_7s.htm
3. Divide the students into teams of 4
4. Have the student teams follow the instructions in the ‘procedure section’ of the student guide
5. Have each students fill out the Currents in water Student Worksheet.

Closing the activity:

• Have students finish student worksheet questions as homework if they need more time
• Discuss as a class what the teams have observed.
• Discuss the relationship between the activities and planet Earth. Ask where circulation like this would occur on Earth. (Takes place in fluids that are heated unevenly, for example, the atmosphere, the hydrosphere [oceans], and even in molten portions of the lithosphere [magma].)
• Explain to the students that air moves in the same way as water when it is heated.
• In the next lesson, we will further explore the relationship between temperature, density, and convection in air and water.

Modifications for Alternative Learners: Limited language students should be able to rely on drawings and diagrams for explanations.

Extension: Demonstrate the Preliminary Exercise in the Teacher's Guide: http://www.teachingboxes.org/catalog.jsp?id=DLESE-000-000-005-588 (the procedure is provided after Part 1's instructions). This exercise demonstrates the concept of density and temperature in water using an aquarium.