Alaska Sea Grant

Investigation 7 - Global Conveyor Belt

Class Time Required 5-12 class periods
Materials Needed
  • Science notebooks
  • Global conveyor belt graphic
  • Project Rubric
  • Student and teacher handouts and graphics
  • Resource materials for research
  • Poster and presentation supplies
  • Student computer access
  • classroom computer connected to internet and projector
Teacher Preparation About one hour to read lesson and background materials, preview graphics and videos, and prepare for class discussion.  
Prior Student Knowledge The previous investigations of the unit should be completed to prepare for this investigation.
Vocabulary Gyre, Thermohaline, Conveyor Belt
Science GLEs Addressed

6th Grade: SA1.1

7th Grade: SA1.1, SA1.2

8th Grade: SA1.1

Investigation 7Overview: In this 5-12 day investigation students discuss and synthesize all of their experiences in the unit. With the help of an animation and a video, they develop a basic understanding of the global thermohaline “conveyor belt.” In small groups, they choose, complete, and present one of the following culminating projects:

  • An examination of contamination patterns after the Exxon Valdez oil spill.
  • An examination of garbage in the ocean and the subtropical gyre.
  • Predictions of the contamination patterns from a hypothetical spill.
  • An analysis of the effects of a hypothetical new landmass in the ocean.

As a class, students brainstorm and design an action project to apply their learning from the unit. Finally, students go back and re-evaluate their answers to Investigation 1 using concepts and vocabulary from the entire unit to make sense of the story of the rubber toys.

Focus Question:

  • How do all of the pieces of the “ocean motion puzzle” fit together?

Engagement: (30 minutes)

Introduce students to the idea of the global conveyor belt using the global conveyor belt graphic and briefly reviewing what they learned about the causes of ocean currents: wind/weather, tides, topography/bathymetry, and density gradients. All of these “pieces” when added together form the global conveyor belt of ocean currents, also called the thermohaline circulation.

The word "thermohaline" is a conjunction of terms referring to "heat" (thermo) and "salinity" (haline). The movement of most mid and deep water in the ocean is driven by changes in heat and salinity, both of which affect density. This global conveyor belt animation shows the general circulation pattern of the ocean, where water sinks in the GIN Sea (Greenland, Icelandic, Norwegian) area of the North Atlantic, becomes cold and travels around the globe, in some places rising to the surface as it warms. Much like the atmosphere and weather, the oceans are constantly “seeking” balance by transporting warm water from the tropics to the poles and cold water from the poles to the tropics.

In class discussion, bring the Ocean in Motion unit full circle as students try to come up with connections between each of their investigations and the complex “conveyor belt” pattern.
Show the video Ocean Currents, to the class after they have learned of the existence of a global conveyor belt. It serves as a summary for all the information presented in the unit, and is a good review for students before they start their culminating unit activity.

Exploration: (180 minutes)

This culminating investigation for the unit will draw on students’ conceptual knowledge of the drivers of ocean currents as they recognize that a conveyor belt of ocean water exists on a global scale.

This activity is an inquiry-based exploration that encourages students to think and problem-solve after choosing their specific focus in the activity. Given a choice or project, students will have the opportunity to develop ownership and creative thinking. Students at this point should be armed with enough conceptual knowledge of what controls ocean currents that they can fashion some inquiry for themselves.

The outcome of this project will be a group presentation addressing the four points below. A project rubric can be used to assess students on the following understandings that each project should address:

  1. Which factors governing the current (wind, tides, density (salinity/temperature) and topography) pertain to your project the most? Why?
  2. How are humans are affected by currents?
  3. How does the weather in the area of your project affect the currents?
  4. What technology pertains to studying the currents in your project?

Background information can be used as a teacher resource to steer students in their thinking or can be presented to the class in a lecture/discussion format, whichever suits the class setup better.

Ask students to choose one of the four projects. Distribute handouts for each project with information, questions, and resources specific to each.
Project 1: Exxon Valdez Oil Spill: This activity examines the specifics of the March 1989 Exxon Valdez oil spill that dumped nearly 11 million gallons of crude oil, the biggest spill ever in U.S. waters.

Project 2: Garbage Patch in the Pacific Ocean :
Because of the subtropical gyre in the Pacific Ocean, circulation in the Pacific Ocean is very defined. In the middle of all gyres is located a calm area that is not under the influence of the currents. Debris and flotsam floating in the gyre often gets jettisoned into the middle area of no current after revolving around the gyre.

Project 3: Hypothetical Landmass :
Students create a landmass of their own imagination with reference back to the earth science/geological concept of the supercontinent of Pangaea. Given the orientation of the landmass, students create currents around the landmass using all their understanding of what creates currents.

Project 4: Hypothetical Spill :
Students design their own spill type and location and model where the detritus will drift based on ocean currents.

Explanation: (60-100 minutes)

Provide time and a forum for students to present their projects to the class using a method of their choice. Depending on the methods they have chosen, you may want to come up with criteria such as time limits or desired qualities (clarity, engagement of audience, aesthetic qualities of posters, etc.). All students should provide a list of sources and cite sources specifically where appropriate.

The projects may be presented as part of a Whole School Celebration of Alaska Seas and Watersheds, and/or you may wish to invite other classes, parents, or community members to view the presentations.

Elaboration (30 minutes - 300+minutes)

Discuss with students: Is there a way that the knowledge you’ve gained in the unit could help you make a difference in your community? Brainstorm ideas for projects that students could design and carry out. For example:

  • A campaign to keep plastic bags out of the ocean.
  • Community education related to emergency preparedness (prevailing winds, storms, tsunamis).
  • A recycling program for bottles, cans, newspapers, etc.

Choose an idea that is feasible, and design and implement an action project as a class.


Most of the formative and summative assessment for this investigation is related to the student project.

As a final assessment, have the students go back to re-examine their hypothesis in Investigation 1 and spend some time updating their hypothesis by writing a new one. Making illustrations and writing captions will help some students express their understanding. Explain that they are expected to have a longer, more detailed hypothesis, and provide a vocabulary list and a concept list (in words or illustrations) so the students can borrow from these to help with their writing.

Teacher Preparation

Tips from Teachers

No tips are currently available.

Read through all of the lesson and background materials, and watch the animations and videos. Prepare to show graphics and video from a computer that is connected to the Internet. Make decisions about the criteria and parameters you will use for student projects. Gather resources for student projects, as well as supplies and equipment that they may need for their final presentations. Research possibilities for action projects in your community.

Do additional research on marine debris to find out the extent of global marine debris problems and the possible solutions that have been discussed.

Invite a guest to the classroom to share experiences from the Exxon Valdez oil spill or another oil spill.

Curricular Connections

Language Arts: How to organize and communicate scientific data in a poster or presentation, citing research sources.

Ideas for adapting to different local environment or context:
A fifth project idea in the culminating activity could be a teacher-developed application of currents relating to the local area (lake, river, coast, etc.)

Materials Needed for Investigation 7:

Student Handouts
  • Science notebooks
Items for Group Display

Global conveyor belt graphic

Global conveyor belt animation

Ocean Currents video

General circulation pattern

Material Items
  • Resources for student projects
  • Books and other materials
  • Poster supplies
Facility/Equipment Requirements

Classroom computer with Internet access and projector
Student access to Internet for research

Alaska Science Standards and Grade Level Expectations Addressed:

6th Grade:
The student demonstrates an understanding of the processes of science by
SA1.1 asking questions, predicting, observing, describing, measuring, classifying, making generalizations, inferring, and communicating.*

7th Grade:

The student demonstrates an understanding of the processes of science by
SA1.1 asking questions, making generalizations, inferring and communicating.*

The student demonstrates an understanding of the attitudes and approaches to scientific inquiry by
SA2.1 identifying and evaluating sources used to support scientific statements.

8th Grade:

The student demonstrates an understanding of the processes of science by
SA1.1 asking questions, predicting, observing, describing, measuring, classifying, making generalizations, inferring, and communicating.*

Essential Questions:

  • What are the patterns of physical changes in aquatic environments?
  • How do they affect us?
  • What are the major weather and ocean circulation systems affecting Alaska?

Enduring Understandings:

  • Physical changes in the aquatic environment occur on a daily, seasonal, and long-term basis.
  • Weather systems and ocean systems have major influences on one another and the dynamics of matter and energy.
  • Science and technology can be used to detect and solve problems.
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