Grade: 6

Goals

1. Learning the factors that create ocean currents (temperature, salinity, wind)
2. Discussion of ocean circulation and its effects on weather

Objectives

1. Recreate surface currents using “wind” in a classroom demonstration
2. Simulate effects of landmasses and submarine features on currents
3. Model the complexity of fluid/current flow
4. Model the effects of temperature on water density/current formation
5. Formulate hypotheses on what effect temperature has on water masses
6. Investigate whether water masses influence climate; discussions

Prerequisites

1. Lessons on formation of wind, atmospheric circulation (pp377-385)
2. Resources 1 and 2
3. Physical properties of matter (pp485-501)
4. Heat (pp561-567)

Benchmarks: 6.6.2, 6.6.4

Materials

1. Drinking straws (flexible is best)
2. Clear, shallow baking dish or tray
3. Food coloring – red and blue
4. Small bowl
5. Petri dish or shallow ashtray
6. Towels
7. Assortment of waterproof objects with irregular shapes
8. Paper punches – the “chads” that fill holes punched out of a piece of paper with a hole punch
9. Map of winds,  ocean sea surface temperatures, currents (http://sealevel.jpl.nasa.gov/education/activities/ts1siac1.pdf)
10. Plastic sandwich bags
11. Clothespins
12. Cold water
13. Hot water
14. Ice

Lesson Description

    The clear shallow trays are the model for an ocean basin. The tray should be filled with enough water to submerge the shallow petri dish/ashtray, but not to wash over the top of the bowl (if inverted and placed on the basin bottom). The exercise can be done in groups, or by the teacher as a demonstration.
    Using a straw, create a surface “wind” by blowing across the surface of the water. Place a drop of food coloring in front of the straw, and watch how the “current” moves around the basin. Students should note the direction of movement relative to the wind, as well as the interaction when the submarine seamount (petri dish) or island (bowl) is placed in the path of the current. NOTE: you may need to reapply food coloring drops between the “wind” and the geographic feature being modeled.
    The chads or hole punches can be used to “map” the formation of gyres in the ocean basin. Sprinkle them on the water’s surface and then create surface currents that travel around the basin’s perimeter. A gyre – a region of calm in the middle of the basin – should form as the chads circulate around the basin. You can simulate the effect of winds at the equator and create two gyres by blowing across the “equator” of the basin. For further emphasis, a map of the ocean may be placed under the basin, and students can generate winds along the latitude lines where the occur naturally (east to west at the equator, west to east at mid-lattitudes), thus creating currents in the “ocean” where they would normally occur. The role that the earth’s rotation plays in shaping ocean currents can also be discussed (Coriolis Effect).
    To simulate the effects of temperature and model deep currents, remove all objects from the ocean basin. Place a rock in a plastic sandwich bag, fill the bag with hot water, and clip it to one corner of the basin with a clothespin. Add a sandwich bag of ice water to the opposite side of the basin, and clip it in place as well. Place a few drops of blue food coloring by the ice, and a few drops of red coloring by the rock. Observe what happens to the dyes over the course of several minutes. The cold dye should sink and diffuse along the bottom of the basin, while the warm dye should remain at the surface. “Wind” may be added if desired, but be careful not to disturb natural mixing.
      The teacher should point out that all of the oceans are connected – one giant world ocean – and that these currents, both surface and deep water currents, move water around the globe. Since water is a great reservoir for heat, ocean currents play a major role in shaping climate. An exercise to prove this is a simple investigation of coastal temperatures at several locations in the world at the same latitude (e.g. San Francisco, CA and Norfolk, VA). Using a weather reporting service, record the temperature at each location for several days, and see how they differ. (http://sealevel.jpl.nasa.gov/education/activities/ts1ssac4.pdf). You should see that at the same time of year, cities on the east coast are warmer than their counterparts on the west coast, due to the warming influence of the gulf stream in the east, and cold water currents that flow south along the west coast.

   

Resources

1. Ocean Current Lessons (http://sealevel.jpl.nasa.gov/education/activities.html) – various classroom lessons and demonstrations, including those described here
2. Animated Oceanography Lessons (http://www.learningdemo.com/noaa/) (NOAA) - **Lesson 8**   **Lesson 15** - excellent animations, videos, and lessons
3. Thar She Blows (http://www.sea.edu/academics/k12.asp?plan=whalingvoyage) – students track historical whaling cruises across the world ocean. Incorporates latitude and longitude exercises and course plotting while allowing students to see how 19th century sailing ships utilized ocean currents
4. Oceanographic Data (http://sealevel.jpl.nasa.gov/education/activities/ts1siac1.pdf) - Maps of winds,  ocean sea surface temperatures, currents
5. Mapping Oceans Game (NASA) (http://sealevel.jpl.nasa.gov/education/jason-1-game.html) – Build your own gameboard of the world’s oceans and play as scientists navigating a research vessel across the high seas in a race to discovery. Progress and points are based on successfully answering questions about earth’s oceans. 
6. Support and lesson plans for marine science teachers (VIMS) (http://www.vims.edu/bridge/) – several lesson plans, activities, educational units, and links to informative web resources for educators and students alike.