Sally Salivates Seashells by the Seashore- Ocean Acidification and the Effect on Sea Shells

Rus Higley, Highline Community College, and Vanessa Hunt, Central Washington University

This activity was selected for the On the Cutting Edge Reviewed Teaching Collection

This activity has received positive reviews in a peer review process involving five review categories. The five categories included in the process are

  • Scientific Accuracy
  • Alignment of Learning Goals, Activities, and Assessments
  • Pedagogic Effectiveness
  • Robustness (usability and dependability of all components)
  • Completeness of the ActivitySheet web page

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This page first made public: Oct 9, 2012


Climate change is an important and complex topic. Multiple consequences including warmer weather are still being evaluated. One recent impact is increased acidification of the ocean and its impact on marine life. In this lesson we review "Acids and Bases" taught in a previous lesson and, through a scientific method, will look at the impact of an acid on different types of shells.

This is an activity for teachers working with students in 6-8th grades in the subject(s) of oceanography & marine biology.

Learning Goals

Science requires its practitioners to share and publish their data. Although there are many ways to do this in school, increasing the students ownership of the issue of ocean acidification is key.

Students will reinforce previous learning of scientific principles including acids/basis and will develop a real experiment using the scientific method.

  1. Review Acids/Bases
  2. Measuring pH
  3. Measuring the effect of adding CO2 to water and explore affect of CO2 on ocean acidity
  4. What are shells?
  5. How are shells affected by CO2?
  6. Publish results through a letter to an elected official including what you'd like the official to do.
  7. One step further, assign students to research the elected official for their area

Context for Use

Educational Standards:

EALR1 Systems
  • Look at a complex situation and see how it can be analyzed in systems
EALR2 Inquiry
  • Questioning and Investigating: Revise a question so that it can be investigated scientifically, and work effectively as a member of an investigative team.
EALR4 Physical Science
  • Matter: Properties and Change: Changes of state and other behaviors of matter can be explained by atomic molecular theory
EALR4 Life Science
  • From Cells to Organisms (shells, bones, exoskeletons as tissues)
  • Changes in ecosystems affect the populations that they support
Mathematics Connections:
  • Employs multiple standards from Mathematics Core Processes

Description and Teaching Materials

For lesson plan please see attachment.

Three components of good science (standardization, replication, and calibration) are stressed. As shells may be provided by learners, encourage options from the different ethnic groups represented by your students.

Ocean Literacy

Earth has one big ocean with many features.
  • Most of Earth's water (97%) is in the ocean. Seawater has unique properties: it is saline, its freezing point is slightly lower than fresh water, its density is slightly higher, its electrical conductivity is much higher, and it is slightly basic.
  • Although the ocean is large, it is finite and resources are limited.
The ocean is a major influence on weather and climate.
  • The ocean controls weather and climate by dominating the Earth's energy, water and carbon systems.
  • The ocean dominates the Earth's carbon cycle. Half the primary productivity on Earth takes place in the sunlit layers of the ocean and the ocean absorbs roughly half of all carbon dioxide added to the atmosphere.
  • The ocean has had, and will continue to have, a significant influence on climate change by absorbing, storing, and moving heat, carbon and water.
The ocean supports a great diversity of life and ecosystems.
  • Ocean habitats are defined by environmental factors. Due to interactions of abiotic factors such as salinity, temperature, oxygen, pH, light, nutrients, pressure, substrate and circulation, ocean life is not evenly distributed temporally or spatially, i.e., it is "patchy". Some regions of the ocean support more diverse and abundant life than anywhere on Earth, while much of the ocean is considered a desert.
The ocean and humans are inextricably linked.
  • The ocean affects every human life. It supplies freshwater (most rain comes from the ocean) and nearly all Earth's oxygen. It moderates the Earth's climate, influences our weather, and affects human health.
  • Everyone is responsible for caring for the ocean. The ocean sustains life on Earth and humans must live in ways that sustain the ocean. Individual and collective actions are needed to effectively manage ocean resources for all.
The ocean is largely unexplored.
  • Understanding the ocean is more than a matter of curiosity. Exploration, inquiry and study are required to better understand ocean systems and processes.
  • Ocean exploration is truly interdisciplinary. It requires close collaboration among biologists, chemists, climatologists, computer programmers, engineers, geologists, meteorologists, and physicists, and new ways of thinking.

Additional Assignments -Write a letter to an elected official. Explain the work done in class and summarize the problem. Publish results through a letter to an editor including what you'd like elected officials to do.

Nautilus Acid Activity (Microsoft Word 42kB Nov9 11)
Teachers' Guide for Nautilus Acid Activity (Microsoft Word 71kB Nov9 11)

Teaching Notes and Tips

Please see attachments.


Assessment can be measured through the completion of a lab manual and the letter to an elected official. Three components of good science (standardization, replication, and calibration) are also stressed. As shells may be provided by learners, encourage options from the different ethnic groups represented by your students.

References and Resources

Scientific equipment-there are many vendors and a lot of money can be spent. Basic but quality pH meters can be purchased for $50-100 from but make sure you get calibration buffers. Pet stores and even spa stores also have lots of options.