CONVECTION CURRENTS
Arund and Arund
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Investigating Convection Currents


Purpose:

The purpose of this investigation is to demonstrate how convection currents form and apply this knowledge to the formation of currents in air, water, and earth materials.

I have discovered that this activity works best as a small group demonstration.


Prerequisites:

Students need to have a good background in the understanding of the concept of density. The following are links to other hands-on lessons that you may find helpful:


Materials:

  1. Clear plastic shoebox (Walmart $1.00)
  2. Waterproof divider (laminated filefolder works great cut to the width of the plastic box)
  3. Food coloring (preferrably red, green, or blue)
  4. Salt
  5. Balances
  6. Hot plate
  7. Beakers
  8. Beaker Tongs
  9. Ice
  10. Old Science catalog
  11. Convection box
    A convection box can be constructed economically...Directions

  12. Incense sticks and matches


Procedure:


Experiment A:



  1. Fill a beaker with 500 mL of tap water.
  2. Measure 35 grams of salt, add to tap water, stir until dissolved.
  3. Add several drops of food coloring to solution; enough to give it a "rich" color.
  4. Fill another beaker with 500 mL of tap water.
  5. Place divider in the center of the shoebox snug to the bottom and sides so that the two types of water do not mix until you are ready.
  6. Starting at the same time, pour each of the beakers of water into the shoebox - salt water on one side of the divider and the plain tap water on the other side of the divider.

    One person needs to hold the divider in place and remove it at just the right time.

  7. Quickly remove the divider and observe the mixing of the two types of water

    AT EYE-LEVEL WITH THE SHOEBOX!

  8. After a minute or two, draw and label your observations.


Experiment B:



  1. Fill a beaker with 500 mL of tap water and add food coloring.
  2. Place beaker on hot plate and heat until you can see steam escaping.

    I pour the hot water for the students!

  3. Fill another beaker with 500 mL of tap water, add ice cubes, and stir until ice is melted and water is very cold.

    It will help to chill the water ahead of time.

  4. Place one end of the plastic shoebox on the old catalog so that it is tilted.
  5. Pour cold water into shoebox and allow the water to settle.
  6. Carefully and slowly pour very warm water into the high end of the shoebox.
  7. Make observations at eye-level with the shoebox.
  8. After a minute or two, record observations in a labeled drawing.


Experiment C:



  1. Light candle in convection box and place under one of the chimneys.
  2. Close glass window and allow inside of box to heat several minutes.
  3. Light incense stick and allow to burn and smoke for a few minutes.
  4. Hold incense stick near outside chimney, oppposite from the chimney over the candle.
  5. Observe the path of smoke in the convection box.
  6. Record observations in a labeled drawing.



Observations:

Directions: Draw and label using color to indicate the temperature of the layers of water for experiments A, B and the path of the smoke in experiment C.

A

B

C

     


Conclusion Questions:

    Procedure A:

    1. How did the salt water and tap water react together after they were allowed to settle for a minute or two?
    2. Why did the two types of water form "layers" in the plastic shoebox?
    3. Which type of water went to the bottom of the plastic shoebox? and explain why it went to the bottom.

    Procedure B:

    1. What happened to the warm water as it was added to the cold water?
    2. What was the purpose of tilting the plastic shoebox before pouring the warm water?
    3. How did the warm and cold water react together after they were allowed to settle for a minute or two?
    4. Why do the two types of water form "layers" in the plastic shoebox?
    5. Which type of water went to the bottom of the plastic shoebox? and explain why it went to the bottom.

    Procedure C:

    1. How was the air inside the convection box warmed? Why is the inside of the box painted black?
    2. What happened to the smoke of the incense stick as it was placed near the opening of the glass chimney opposite the candle?
    3. Explain what happened to the smoke after it entered the convection box.
    4. Explain why this occurred (in reference to #3).


Applying What You Learned:

  • Explain how temperature affects the circulation of ocean water.

  • Find out how differences in the temperature and salinity of the water help create ocean currents.

  • Investigate The Theory of Plate Tectonics to discover how scientists explain how continents can move.

  • How does the weather work?

  • Investigate convection on the sun.


Assessment:

Scoring Rubric
Observations A Observations B Observations C Questions Application Total Points
20 pts. 20 pts. 20 pts. 24 pts. 16 pts. 100
           


  • 100%- ALL Data is Complete and Accurate
  • 80% - MOST data is complete and accurate, however, a few mistakes were made
  • 50% - SOME mistakes were made, data lacks completeness and/or accuracy
  • 20% - MANY mistakes were made, almost totally incomplete and/or inaccurate
  • 0% - NO attempt was made to complete this section and/or totally inaccurate


Percents of Total Points
Total Pt. Value 100% 80% 50% 20%
24 pts. 24 pts. 19 pts. 12 pts. 5 pts.
20 pts. 20 pts. 16 pts. 10 pts. 4 pts.
16 pts. 16 pts. 13 pts. 8 pts. 3 pts.

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2/24/03


This lesson was created through an intensive technology training program for teachers, GirlTECH '96, sponsored by the The Center for Research on Parallel Computation, funded by the The National Science Foundation.


© 1996-2003 Georgia Louviere