Ocean Currents; Marine Science Activities for Grades 5-12

What causes ocean currents? Learn how wind, temperature, salinity, and density set water into motion, and they make an in-depth investigation of the key physical science concept of density. This series of activities will cover these topics. For grades 5-12.

Ocean Currents, Part I: Surface Currents {Wind and Temperature}

Ocean Currents, Part II: Salinity Currents

Ocean Currents, Part III: Temperature Currents

Ocean Currents, Part IV: Polar vs. Tropical Water

Ocean Currents, Part V: Ice Cubes Demonstration

Ocean Currents, Part VI: Layering Liquids

Ocean Currents, Part VII: Explorers and Ocean Currents

Additional Activity: Current Events

Literature Connections: 

Adrift: Seventy Six Days Lost at Sea, Steven Callahan, Grades: 7–12
Bounty Trilogy, Charles Nordoff and James Norman Hall, Grades: 7–12
By the Great Horn Spoon!, Sid Fleischman, Grades: 4–8
Call It Courage, Armstrong Sperry, Grades: 3–6
The Cay, Theodore Taylor, Grades: 6–8
Darwin and the Voyage of the Beagle, Felicia Law, Grades: 4–8
Endurance: Shackleton's Incredible Voyage, Alfred Lansing, Grades: 7–12
Island of the Blue Dolphins, Scott O’Dell, Grades: 5–12
The Magic School Bus On the Ocean Floor, Joanna Cole, Grades: 1–4 (For younger grades, but still has some good information.)
Moby Dick, Herman Melville, Grades: 7–12
The Robinson Crusoe, Daniel Defoe, Grades: 7–12
Treasure Island, Robert Louis Stevenson, Grades: 7–12
The True Confessions of Charlotte Doyle, Avi, Grades: 5–8
The Voyager’s Stone: The Adventures of a Message-Carrying Bottle Adrift on the Ocean Sea, Robert Kraske, Reading Level is Grades: 3–6, but the story is wonderful and illustrations very informative.
Windcatcher, Avi, Grades: 4–7
The Wreck of the Waleship Essex, a Narrative Account, Owen Chase, Grades: 7–12

Sources and Resources:

• Ocean Currents, Catherine Halversen, Kevin Beals, Craig Strang, Lawrence Hall of Science

Ocean Currents, Part VII: Explorers and Ocean Currents

Now we get a chance to look at actual routes explorers took in terms of what we have learned about ocean currents.

Sam traced the routes of Magellan's first trip around the world (1519-1522)...

Source: Ocean Currents, Catherine Halversen, Kevin Beals, Craig Strang, Lawrence Hall of Science

 and then laid this tracing over surface and...

Source: Ocean Currents, Catherine Halversen, Kevin Beals, Craig Strang, Lawrence Hall of Science

deep currents maps to see how the trip probably was affected by currents.

The green arrows represent where surface currents crossed Magellan's route. The blue arrows represent where deep currents crossed Magellan's route. Did he use the currents to his benefit or did he have to fight the currents at any point? What about places with little current?
He went over Magellan's route, coloring it purple where it went with the currents and orange where it did not get the current's help. Sometimes he even went against the current.

We then did the same thing with Captain Cook's second trip around the world (1772-1775).

He immediately saw that Captain Cook's route almost always followed the currents. We noted that it was over three hundred years between the two trip and supposed that perhaps they had learned much more about how to take advantage of the currents over that period of time.

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Originally posted Feb 24, 2011

Ocean Currents, Part VI: Layering Liquids

 The ocean is made up of layers of water of different densities. Cold water is denser than warm water, water with salt is denser than fresh water. The more closely packed the molecules in a substance, the denser the substance.

Sometimes you will see little currents in the straw as one type/color of liquid passes another.

This week I challenged them to apply the information that they have learned to create four distinct layers in straw cylinders using only colored water and salt. 

Please excuse the messiness of our school table.
 I usually clean it off after every activity, but has been one of those crazy weeks for us.

For this experiment you will need: 

• 4 Styrofoam cups or insulated containers
• kosher salt
• plastic straws
• medium raw potato
• medicine droppers
• a package of food coloring

Have students write in their journals a key to the colors:
red-hot and salty
blue-cold and salty
yellow-hot and fresh
green-cold and fresh

 Have four containers to hold water and label them as above, adding about 15 drops of the appropriate food coloring to each container. Fill the containers with water, two with hot water and two with cold. Add 1/3 cup of kosher salt to both the red and blue water. Stir. Add ice to the blue and green containers.

Cut potato into 1'' thick slices. Cut two straws in half for each student. Insert straw into the potato at a 45 degree angle.

 

Sometimes the water will leak out of the bottom. You can ignore it if it is a small amount, or you can take the straw out of the potato over a sink, rinse out the straw and start over again at a new place in the potato, trying to push the straw in deeper.

Have your students decide what order they think the liquids will layer according to density. Have them try out their predictions by adding a tiny bit of the liquids to the straws so that they fill the straw about 1/2 inch, starting with the most dense and adding them one at a time.

 Your students should have layers, starting from the bottom, or the most dense, blue (cold and salty), red (hot and salty), green (cold and fresh), and yellow (hot and fresh).

We got a different result however, in ours. That happens sometimes. In that case, we explore why we got discrepant results. Our layers were, starting with the bottom, or most dense, red (hot and salty), blue (cold and salty), green (cold and fresh), and yellow (hot and fresh). The best explanation we could come up with is that our hot water may have allowed more of the salt to dissolve into the water than the cold. Do you have any other possible explanations?

source: Ocean Currents, Catherine Halversen, Kevin Beals, Craig Strang, Lawrence Hall of Science

Looking at a map, discuss where they think the different types of water might be found.

Cold and salty water is found in Antarctica and the Arctic because the water freezes, leaving the remaining liquid water very salty and cold.

Cold and fresh water is found in places where northern cold rivers drain into the ocean, like in Canada and Siberia.

Warm and salty water is found in areas where the water is warm, but due to the evaporation of water and low river inflow, it is very salty, such as the Mediterranean and Red Seas.

Warm and fresh water is found in places where warm rivers drain into the ocean such as the Amazon and Congo Rivers.

As the waters enter the ocean, they form layers which may last a long time and move long distances.

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Originally posted: Feb 18, 2011

Ocean Currents, Part V: Ice Cubes Demonstration

We have learned in the past few weeks that salt water is more dense than fresh water and that cold water is more dense than warm. How do the factors of salinity and temperature combine?

The two jars react very differently when the colored ice cubes are added to them.

We have learned in the past few weeks that salt water is more dense than fresh water and that cold water is more dense than warm. How do these factors, salinity and temperature, combine?

Before hand, make some colored ice cubes by adding food coloring to the water in an ice cube tray. We did this the night before.

Fill two identical jars about 3/4 full with tap water. Add about 1/4 cup Kosher salt to one of the jars, mix thoroughly and let sit. Can your students tell which one of them has salt water and one fresh water (without tasting)? Very carefully add 3-4 of the colored ice cubes to each jar. Add the same amount to each jar. Do not bump or disturb the jars.

Where is the colored water going? Which jar is the ice melting faster? What would this indicate?

Can you see a current flowing toward the bottom as the icy water carries the food coloring down with it as it sinks? As the temperature evens out, the food coloring mixes throughout the jar. This is the fresh water jar. The icy water is denser than the room temperature water and sinks. The sinking of the icy water helped set up currents in the jar which quickly mixed the icy water and the room temperature water.

In the other jar the ice melted more slowly and the food coloring formed a layer at the surface. Because the ice cubes were made of fresh water, as they melted, the water floated at the top of the denser salt water.

To demonstrate for the little boys how the salt-water could be more dense than fresh water, I took a cup with some marbles in it and told them that this is just like the water molecules and then added some salt to the cup. This is like the salt molecules, which are able to fit in between the water molecules, making the entire substance more dense.

The densest water in the ocean is formed around the Antarctica because the water is very cold and very salty. This combination causes it to become very dense and sink to the bottom of the ocean basin surrounding Antarctica. This water then travels north as the densest water in the ocean.

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Originally posted Feb 11, 2011

Ocean Currents, Part IV: Polar vs. Tropical Water

For this experiment, you will need 2-6 to 8 oz. Styrofoam cups, 2 push pins, a clear rectangular 6-qt. container such as a small aquarium, 20 marbles, red and blue food coloring, hot, cold and room temperature water.

Place marbles in the cups to keep them from floating or tipping. Pour icy-cold water in one of the cups and add 6 drops of blue food coloring. Stir. Pour very hot water in the other cup and add 6 drops of red food coloring. Stir.

Stick a push pin in each cup at the level where the hole will be just below the surface of the water in the large container. The pins should be at the same level in both cups. Leave the pins in the cup. Place white paper or cloth behind the container so that any water movement is easily seen. Carefully place the cups in the container of water with the push pins facing away from each other. Pull out the push pins in each cup. Bend down so that you are eye level with the experiment.

Continue to add the appropriate temperature water to the two cups to keep the water level in each cup almost to the top.
Where does the clear (room temperature) blue (cold) and red (hot) water start and where do they end up?

You may also notice a phenomenon called upwelling. It is when cold water hits a solid such as land, or in this case, the side of the aquarium, the water goes up and ends up just under the layer of hot water. You can see how this would create additional currents.

 Based on your observations, what generalizations can you could make about what happens when water of different temperatures meet?

Alex's science journal page

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Originally posted Feb 4, 2011

Ocean Currents, Part III: Temperature Currents

The set up for this experiment is the same as the last one, so if you have any questions, refer to that one, which I have written in more detail.

Fill one bottle to the very top with hot tap water. Screw the tornado tube onto this bottle. Fill the other bottle almost to the top with icy cold tap water. Add 6 drops of food coloring to the cold bottle and shake well. Finish filling the cold bottle to the very top with more cold water. 

Place the yogurt lid over the top of the cold water bottle. Press down firmly on the yogurt lid, invert the cold water bottle and quickly place it over the opening of the tornado tube attached to the hot water bottle. Carefully slide the yogurt lid away, allowing the two bottles to join together with the tornado tube in between them. Screw the cold water bottle tightly on the tornado tube. Lay the bottles gently on their side on the white dish towel to catch any drips. Tighten the tornado tube if more than a few drops leak from either bottle.

Other than that, do not disturb the bottles at all. Bend down to eye level and observe any movement for at least 5 minutes.

The more dense cold water sinks to the bottom and the less dense hot water floats on the top.

Feel the bottles for differences in temperature. Do you see any other signs of temperature difference, such as condensation?

You can easily feel the layers of water of different temperatures.

Where does the movement of the colored water in the bottles make the water end up?.

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Originally posted Jan 28, 2011

Ocean Currents, Part II: Salinity Currents

Salinity and temperature differences create masses of water with different densities. Gravity causes more dense water to sink below less dense water As a result, the less dense water rises. These factors create currents.

 For the next few experiments, we will explore how water of different salinity levels and of different temperatures react. Our first experiment will be with water of different salinity levels.

You will need:

• 2 identical plastic bottles (about 12-16 ounces) with straight sides and threaded mouths (water bottles are good)
• a tornado tube
• a white dish towel
• salt, Kosher preferred because it leaves the water more clear
• food coloring (any color but yellow)
• a yogurt or small container of sour cream lid with the rim cut off
• room temperature water
• a tablespoon

Fill two bottles with room temperature tap water. Fill one bottle to the very top and leave about an inch of space at the top of the second bottle. Add approximately  4 Tablespoons of salt (preferably Kosher salt as it leaves the water clear) and six drops of food coloring to the bottle with the space at the top and shake well. This is the salty water bottle. Screw a tornado tube tightly onto the salty water bottle. Finish filling the salty water bottle to the very top on the tornado tube with tap water.

Place a yogurt lid with the rim cut off over the top of the fresh water bottle. Press down firmly on the yogurt lid, invert the fresh water bottle and quickly place it over the opening of the tornado tube attached to the salty water bottle.

Carefully slide away the yogurt lid, allowing the two bottles to join together with the tornado tube between them. Screw the fresh water bottle tightly into the tornado tube.

Lay the bottles gently on their sides on a white dish towel to catch any drips. Have the one side of the dish towel bend up by attaching it to a box or a wall if one is close so that you can see the movement of the colored water. Try to disturb the bottles as little as possible. You may have to tighten the  tornado tube if you see more than a few drops leaking from either bottle.

Bend down to eye level and watch the movement of the water. At first the colored water will slowly seep into the clear water bottle and gather a little on the bottom of the tube. 

 If you continue to watch the bottles for at least 5 minutes, you will see that the bottles pretty evenly divide, with the colored water on the bottom and the clear water on the top.

 What do you think this tells you about when waters of different salinity levels come in contact with each other?

The water with the most salt and therefore the most density, will move to below the water with less salt and therefore less density. This movement can create a current.

If you like, you can sketch first the set up, labeling which bottle has fresh water and which has salty water, and then using colored pencils, show the movement of the colored water in the bottles and where it ends up.

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Originally posted Jan 21, 2011