back to list of labs A SODIUM: CHLOR...RIDE

Up, Up, and Away!

Descriptions:

In this activity, students will investigate the effect of wind, temperature, and density on the formation of ocean currents.

Materials:

200 mi beaker
clear plastic rectangular tub (4 L)
food coloring: red, blue, yellow
tap water
salt

Procedure:

Wind Investigation:

plastic spoon
sheet of paper
hair dryer
ice cubes

1.  Begin  the  lesson  with  the  initiating  questions  or  choose  some questions of your own. Listen to the students' responses and try to determine what the students already know about currents, factors that affect current, and the ways in which currents affect climate. Use this information to alter the lesson to meet the needs of the students.
2.  Divide students into groups.  Supply each group with a hair dryer to simulate wind action, and a plastic tub about two-thirds full of water.
3. Have students blow air from the hair dryer across the top of the simulated ocean (plastic tub), noting how the waves move.

Density Investigation:

1..  Distribute to each group red, blue and yellow food coloring, 2-200 ml beakers, a clear plastic container, salt, ice cubes, a plastic spoon, and a sheet of paper.
2.  Have students fill one of the 200 ml beakers with water, adding a few drops of blue food coloring and dissolving a teaspoon of salt in.the liquid.
3.  Have students fill the plastic container with water and stir a few drops of red food coloring in the water.
4.  Have students tear the sheet of paper into small pieces and sprinkle the paper onto the surface of the water in the plastic container.
5.  Have students gently pour the blue salt water solution (Step #2) down one side of the container noting the movement of the paper.
6.  Have students leave the container undisturbed and continue to make and record their observations every 5 minutes for the next 20 to 30 minutes .
7.  Repeat steps 2,3, and 4. To the second beaker, add water, a spoonful of salt, a few ice cubes and some yellow food coloring. Pour the blue salt  water into the plastic container as you did in step 5, then add the yellow salt water in the same way noting the number of layers in the plastic container. Have students record their observations.

For Your Information:

Ocean currents caused by wind patterns are called surface currents. Deep ocean currents are mainly due to temperature changes and density. Currents are important to life on Earth because they moderate temperature, bringing warm water into the higher latitudes and cold water into the lower latitudes. These currents also bring nutrients to nutrient-poor water.  Any change in the current affects the temperature, humidity and life processes of the area. In this experiment, the blue salt water moves below the red fresh water causing the paper to move. Adding salt increases the density of water. The denser saltwater moves under the less dense fresh water forming a current of water near the bottom of the container.
 Since cold water is more dense than warmer water, when students pour the iced, salt water into the plastic container, the cooler, yellow water should move under the first two layers and fall to the bottom.

Teaching Tips:

You might choose to do the wind investigation on the overhead as a class demonstration. Be careful using food coloring. It stains clothes.

Assessment:

 Pretending that they are a plankton, whose movements are affected by both surface currents and deep currents, have each student write a short story describing their travels through the ocean. They should include information about how they are affected by wind, density, and temperature.

References:
NSTA Galapagos Jason Curriculum, 1991
Prentice-Hall, Vovage of Exploration, 1991.
Glencoe, Inteerated Science Activity Book
 

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