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What does ocean acidification mean for shell-building marine life? (gr 6-8)

Author Information

* Name: Dr Sandi Smart

* Affiliation: The University of Alabama, Department of Geological Sciences

Contact Information (Email, Twitter, Personal Website, etc.):

* Contact:

* Year contributed: 2024


  • Grade Level: grades 6 - 8
  • Alabama Course of Study:
  • SC15.6.7
  • SC15.6.14
  • SC15.6.15
  • SC15.7.5
  • SC15.7.6
  • SC15.7.7
  • SC15.7.11
  • SC15.8.2
  • SC15.ES.12


The ocean has taken up about one third (30-40%) of the carbon dioxide (CO2) released into the air by human activity (mainly fossil fuel burning, cement production, deforestation). This CO2 is increasing the acidity of the ocean (lowering its pH), and making it more difficult for shell-building marine life to build their shells.

First, students are asked to think of some marine organisms that have shells or other hard parts. They learn that there are two ingredients needed to build a these shells/corals: (1) calcium, and (2) carbonate.

This lesson introduces acid and bases using everyday examples (e.g., lemon juice vs bleach), and explains how we use the pH scale (0-14) as a measure of acidity. Students will brainstorm sources of CO2 (our breath, burning charcoal, driving cars etc.), and to consider how adding CO2 to water can change the acidity/pH of water (using club soda/seltzer water as an example).

Students will play The Ocean Acidification Game which illustrates how ocean chemistry has changed through time from the 1850s (pre-industrial) to the present.

Older classes can plot their results on a line graph (placing stickers on a printed chart with axes, or using graphing paper or an online plotting tool like They can compare this with actual data measured (e.g., the Mauna Loa CO2 record, Students are asked to notice any “trends” (patterns with time), and to “predict” (approximately) what CO2 levels (and corals) will look like in the future (e.g., 2050) if these trends continue.

We finish with a reflection on why this all matters, and what our society (governments, companies etc.) needs to do, and what we can do as individuals to help protect the ocean and the health of our planet.






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alabama/what_does_ocean_acidification_mean_for_shell-building_marine_life.txt · Last modified: 2024/06/04 10:16 by alabama