Understanding Oceans
  • Normal Ocean Chemistry Mat
    Normal Ocean Chemistry Mat

This lesson is appropriate for children ages 11 and up.  

*The Understanding Oceans mats are NOT included with a purchased Molecules Set, but they are free to download below.

The Understanding Oceans group of 3 lesson mats teaches why oceans are becoming more acidic. This lesson module also introduces the pH scale.

Students first model how increasing levels of carbon dioxide in the air can alter chemical reactions in the ocean water. They will compare the chemical reactions shown on “Normal Ocean Chemistry” mat with “Ocean Acidification” mat. These activities recreate important chemical reactions in the ocean using LEGO® bricks to model the atoms.

After completing the first two activities mats, the students engage with the “Ocean and pH Scale” mat.

This activity is highly recommended to help students understand the consequences of ocean acidification.

Several short activities explain what the pH numbers mean and include the following objectives: reinforcing the essential chemistry concepts for ocean acidification, making predictions for our ocean’s pH in the future, and providing suggestions for what students can do to slow down ocean acidification.

NOTE 1: Looking for a lesson to teach pH? Teach the “Oceans and pH Scale” mat first to introduce the concept of pH. Next, teach the normal and ocean acidification activities as important examples in nature where pH is critical to life in the ocean.
NOTE 2: Need to teach about mercury as a toxin in fish? Teachers looking for materials about mercury bioaccumulation or ocean food chains will find the mat, “Toxic Mercury in Our Environment” included here for your convenience. The Mercury mat also can be found under Various Additional Modules.
Lesson Plan
Lesson 1: 
Normal Ocean Chemistry Mat and Ocean Acidification Mat required
Lesson 1 is designed to help students learn how increases in the amount of carbon dioxide in the air can affect normal ocean chemistry.
  • Students will first model a normal ocean to observe the chemical reactions that occur in the ocean.
  • Next, the students will model the chemical reactions that produce ocean acidification. The initial number of carbon dioxide molecules in the air above the water will be increased to observe what happens. A greater number of carbon dioxide molecules will be absorbed by the ocean.
  • The increased carbon dioxide in the water has consequences now. The increase in free H atoms can make it too difficult for sea creatures to build chalk for their shells.
Lesson 2:
Oceans and the pH Scale Mat required
Lesson 2 is designed with 4 short activities on one large mat, to be completed in order.
  • In the first activity, students work with white LEGO bricks that represent H atoms. In this way, students begin to visualize that the ‘H’ in pH as referring to the number of free hydrogens. It is not necessary to have younger students relate the pH numbers to negative exponents, however the negative log scale is given in the small inset as way for a teacher point out the connection.
  • Seeing the pH numbers range from 0 to 14 may be helpful for some students. The other activities on the mat have additional objectives-- such as making predictions for our ocean’s pH in the future, and providing some actions to help slow ocean acidification.
Lesson 3: (Optional)
Toxic Mercury in Our Environment Mat required
For convenience only, this Mercury mat is placed in with Ocean materials. Note: The science of mercury biomagnification has little to do with acidification.
  • Mercury is a poison. This lesson focuses on how mercury moves through the environment and how the mercury may accumulate in the fish humans eat.
  • Mercury sources contribute both to the levels of mercury in air and in water all around the planet.
  • Microorganisms found in soil take elemental mercury and create methylmercury molecules.
  • The biomagnification of methylmercury in fish modeled. This example provides a hands- on activity, reinforcing the concept of food chains in the ocean.



Students should be familiar with the concept of LEGO bricks as atoms. Instructors need to add their own age-appropriate information and sources about the effects of mercury toxicity and healthy dietary consumption of fish.
To create your own mats, download and print the documents above. Important directions for printing: Set the printer scaling to "0%" or "none" so that the LEGO bricks on the printouts are actual size. Print large mats in 2 sections, tape together, and laminate if possible; or place inside a plastic sleeve. Keep these instructions with the LEGO kits.

For educators planning to teach only the "Understanding Oceans" lessons, you may collect the following fewer number of bricks per student kit:

  • 12 red 2x4 bricks (oxygen atoms)
  • 4 black 2x4 bricks (carbon atoms)
  • 4 grey 2x4 bricks (mercury atoms)
  • 1 green 2x4 brick (calcium atom)
  • 12 white 1x2 bricks (hydrogen atoms)

Note: "2x4" and "1x2" refer to the number of bumps on top of the LEGO bricks.

Standard LEGO bricks can be used and will serve for our Photosynthesis and Chemical Reactions lessons as well. The  Atoms and Molecules Layout Mat shows the recommended LEGO bricks. We chose these bricks because they can be used to illustrate a number of chemical and biological concepts. Their colors match those commonly used in other chemical models, though other colors may be substituted. The layout mat can also be used as an easy clean up tool to check if students have all their bricks.

Building blocks (such as LEGO) can be purchased from toy manufacturers or the LEGO.com website. You might also arrange a LEGO brick donation with your local Parent Teacher Association.

Curriculum Standards

Coming Soon!

Contact us if you would like to learn how to use the materials at our next workshop or if you would like to inquire about acquiring a classroom set including LEGO bricks.

LEGO®, the LEGO logo, and the brick and knob configurations are trademarks of the LEGO group, used here with permission. ©MIT. All rights reserved.