Summer Lesson Plan #1: "Current" Plastic Problems



"Current" Plastic Problems

  This lesson provides students with the opportunity to develop and enhance the valuable skill of scientific inquiry. This investigation involves studying the thermohaline circulation of the ocean, the oceanic gyres in the ocean, and how plastic travels through both. Through this process, students gain an in-depth understanding of the effects plastic pollution can have - from investigating the issues that arise from salinity gradients, to interpreting how plastic size and weight will contribute to its movement. Students will be challenged to think critically about how they would solve the issue of plastics being moved throughout the ocean. 

Students Will Be Able To:

[1] Identify the thermohaline circulation pathway

[2] identify the oceans main gyres

[3]understand how temperature and salinity of ocean water can affect plastics

This activity works best as a review of scientific concepts explored in class prior to completing this lesson plan. Students should be familiar with the concepts of biotic and abiotic factors, water density, temperature, and how environmental and human impacts influence ecosystems. Please see the section “Helpful Information”  for a glossary of terms, and a map of the Thermohaline Circulation pathway at the end of the "Task" section.


1) Understanding the Ocean Current (3 min). Have your class watch our video titled “How does your plastic end up in the Arctic” and study the map at the end of this section.

Background information needed:

  • our many oceans make up one big global ocean
  • the Thermohaline circulation AKA the “global conveyor belt” has warm and cold sections
  • Animals use the thermohaline circulation as a “highway” around the ocean
  • plastics are more likely to sink in colder, saltier water, but more likely to degrade when in sunny, shallow water
  • plastics can enter gyres easily, but cannot escape them easily

 2) Discussion (10 min). Divide your class into groups, and use these questions to guide a “Think-pair-share” or “jigsaw” activity:

  • What are the different problems about plastics being in warm water vs being in cold water? Is one more favorable than the other? Why?
  • What are the issues about plastics being caught in a gyre vs being caught in the global current? Is one more favorable than the other? Why?

3) Activity (20 min). Challenge your groups to prototype a method for either cleaning up the Thermohaline Circulation OR the ocean gyres. Once decided, give the groups 15 minutes to design and draw the prototype to help clean up their chosen ocean feature. Have them present it to the class.

Things for the students to consider:

  • What is their device made of?
  • How is it powered?
  • How does it distinguish animal from plastic?
  • What is specific purpose? How does it achieve that purpose?

4) Direct Action (60-90 minutes): Participate in the #BePlasticWise challenge “Go Outside and Play” and organize a “plogging” clean-up at a local watershed. Hand out garbage bags and gloves, and have a “sharps” container. Have your students wear waterproof footwear so that cleaning in or near water is easier.

 Challenge your students to find garbage that:

  • Has been affected by a current
  • Has been affected by weather
  • Is floating in water
  • Is submerged in water

Discuss with the students what they how that local watershed is connected to the ocean, and the pathway of that garbage if it hadn’t been cleaned up.

Helpful Information:


  • Thermohaline Circulation: is a part of the global ocean circulation that is driven by water density. The adjective thermohaline derives from thermo- referring to temperature and -haline referring to salt content.
  • Ocean Gyre: any large system of circulating ocean currents, particularly those involved with large wind movements. There are 5 main Ocean Gyres: North Pacific, South Pacific, North Atlantic, South Atlantic and Indian.
  • Salinity: the measure of all the salts dissolved in water.

Thermohaline Circulation Map:

Learning Objectives

Ocean Literacy - Prescribed Learning Outcomes

Principle 1 = The Earth has one big ocean with many features

  • All oceans connected via thermohaline circulation
  • Gyres are found adjacent to the thermohaline circulation
  • Plastic can travel globally via ocean currents

Principle 4 = The ocean is a major influence on climate and weather

  • The Thermohaline circulation affects global temperatures
  • Heat is lost to the atmosphere when a warm current turns into a cold current
  • UV rays from the sun degrades plastics

Principle 5 = The ocean made the Earth habitable

  • The Thermohaline circulation supports human life
  • Ocean health is connected with human health

Principle 6 = The ocean and humans are inextricably interconnected

  • The plastic pollution in the ocean is a man-made issue
  • Plastic pollution in the ocean is having a negative effect on sea life, and in turn, a negative effect on humanity

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