ENGAGEMENT
Ocean waters are constantly
on the move. How they move influences climate and living conditions for
plants and animals, even on land. Currents flow in complex patterns affected
by wind, the water's salinity and heat content, bottom topography, and
the earth's rotation.
® Using the Oceanview data display tool, or the Internet, teacher displays several maps of sea-surface temperature, ocean salinity, and ocean circulation. Raise questions/elicit responses about these maps, identifying students' prior knowledge/misconceptions about these topics.
• Probe students for patterns in global sea-surface temperature.
• What is causing the temperature regions seen here?
• Have students hypothesize what happens to ocean water as the temperature increases.
• Discuss the properties of seawater (heat capacity, salinity, density, etc)
• Question students about the ways in which salinity levels change as latitude increases.
• Why is salinity so much higher in the subtropical latitudes than it is in the tropics?
• Are these patterns consistent across the
entire planet? What might change the salinity of a given area?
EXPLORATION
Students should now be
given the opportunity to explore some of these ideas using the Oceanview
data display tool. The teacher should act as a facilitator, helping students
to frame questions by asking questions and observing. This is the opportunity
for students to test predictions and hypotheses, and/or to form new ones.
The following is a list of suggested questions and buoys that may or may
not lead the students to finding the answers. The beauty of science is
that there may not always be a correct answer, so if the students do not
find their expected answers by comparing two buoys, ask them why! What
kind of situations may need to be factored into the collection of the
buoy data? (weather events, human disturbance, etc) Have the students
try graphing different dates for the buoys in question to see if their
results differ.
1. Which area has warmer surface water temperatures?
2. Which area has higher salinity?
3. Are these the results that you would have expected? Why or why not?
4. Do you get the same results in January as you do in June? What about November?
® Now compare the North Carolina Coast buoy to the Labrador buoy. Select salinity and temperature as the parameters.
1. Which area has warmer surface water temperatures? Is this what you would expect?
2. Which area has higher salinity levels?
3. Why is there such a drastic difference in salinity for these two areas?
4. Is it like that all year round?
5. What would you predict the dissolved oxygen to be like for these two areas?
6. Were your predictions correct?
® Compare the North Carolina
Coast buoy to the Portugal buoy. Compare each of the parameters for the
two buoys.
1. Are these
two buoys located at similar latitudes?
2. Would you
predict that they would have similar temperatures throughout the year
or will they be different? Test your hypothesis by selecting temperature
as the parameter and various months of the year.
3. Were your
predictions correct? Why or why not?
4. Now do
the same for salinity and dissolved oxygen. Were your predictions correct?
Why or why not?
® Select the Labrador
buoy and the Ireland buoy. Select temperature and salinity as the parameters.
1. Are these two buoys located at the same latitude? If not what is the
difference?
2. Would you expect that they would have similar surface water temperatures?
Why or why not?
3. Scroll through the various months of the year to see if the temperature
and salinity patterns are consistent.
4. Any ideas why there is such a drastic difference in water temperature
and salinity if these two buoys are located so close to one another?
® Continue to compare buoys in the Atlantic Ocean, probing students with similar questions. See if they begin to pick up on patterns/trends in the data. Extend the questioning to include any other topics that you may want to include in your lesson.
EXPLANATION
Students should now be
involved in an analysis of their exploration. Encourage the students to
explain concepts in their own words, asking for evidence and clarification
of their explanation. Students should use observations and recordings
in their explanations. At this point, you should provide definitions and
explanations using students' previous experiences as a basis for this
discussion. Perhaps, to start the discussion, you can ask if any of the
students have been out to the Gulf Stream off of the North Carolina coast.
If so, have any of them noticed a difference in water temperature or air
temperature? The following are some suggested topics that you may want
to define/explain:
- Properties of sea water: average
salinity, temperature/density relationships, salinity/density relationships
- Hydrologic cycle: specifically,
precipitation and evaporation, and their global effects on seawater.
- Water displacement/ global
wind belts
- Coriolis effect
- Global sea temperatures
- Warm water/ Cold water currents
EXTENSION
Students should apply
concepts and skills in new (but similar) situations and us formal labels
and definitions. Remind students of alternative explanations and to consider
existing data and evidence as they explore new situations.
® Provide students with
a blank map of the earth and colored pencils.
® Using the Oceanview
data display tool have the students select various buoys in the northern
Atlantic and graph their data to determine the circulation of the North
Atlantic Gyre
® Have them use red colored
pencils to represent/draw warm currents and blue colored pencils to represent/draw
cold currents and draw their projected currents on the map.
® Go over the correct
ocean circulation pattern with them and label any of the names of the
currents that you would like for them to know.
® Lead them in a discussion
of other global ocean currents, predicting which way the water flows and
its temperature. Have students complete their map based on your discussion.
You may want to do this with them with the aid of an overhead projector.
® The students can then
check the accuracy of their work against the ocean circulation map provided
by Oceanview, by selecting the 'show circulation' button.
Evaluation can and should take place throughout the learning experience. You should observe students' knowledge and/or skills, application of new concepts and a change in thinking. An optional evaluation activity would be to apply their new knowledge to solving a problem that involves similar concepts, but also incorporates a more abstract thinking process. This will help you to quantify the students' understanding, and to determine weather the concepts need more reinforcement. If you intend to teach about the effects of ocean circulation on global climate, then the following activity could potentially lead into the start of a new learning cycle:
Same time, Same Place, Different Climate
Wilmington, NC and Los Angeles, CA are both located at approximately 340 N latitude. Do you think that we have the same climate here on the east coast as they do over on the west coast? How can you find the data that will answer this question?® Students can go to
www.weather.com and select the monthly
climate data for the two cities. Help them to notice patterns in rainfall
data, particularly during the summer months for the two cities. In the
interest of time you may want to have these data already printed out for
them to use.
® Using the climate data,
probe the students for answers to the following questions (either orally
in a discussion, or have them answer questions on paper)
•
Which city has warmer summers?
•
Which city has colder winters
•
Which city receives more precipitation annually?
•
What is the difference in average precipitation between the two cities
during the summer months?
•
ANY IDEAS WHY?????
® Using the Oceanview
data display tool, compare the data for the buoy off of the North Carolina
coast with the buoy off of the California coast. Select salinity as the
parameter.
• Which coast experiences warmer water temperatures during the summer
months?
• What is the difference in temperature?
• Why do you think these two cities that are at the same latitude
are experiencing such a difference in ocean water temperature?
® Change the parameter
to salinity. Ask the students the following questions:
•
What happens to the salinity of ocean water as the temperature increases?
Why?
•
What is causing this change in salinity?
•
Does the data from the two buoys support your hypothesis? Why or why not?
•
Which coast experiences higher salinity?
® Have the students select
temperature and salinity as the parameters for their graphs. Also, have
them graph the data for June, July, and August. They should then compare
their climate data during these months to their ocean data.
•
What effect does warmer ocean water have on the hydrologic cycle?
•
Does warmer or colder water lead to more evaporation?
•
Which city experiences more summer rainfall? Does this city have warmer
or colder water temperatures during the summer?
•
What conclusions can you draw from comparing these data?
The following link provides a similar activity comparing ocean currents
to climate:
http://seawifs.gsfc.nasa.gov/OCEAN_PLANET/HTML/oceanography_currents_4.html
This may be helpful in reinforcing the concept after the exploration
and evaluation.