Lesson 5a – Ocean Acidification Experimentation

Description: The purpose of this lesson is to allow students to complete research on the topic of ocean acidification and to work toward answering their interest group’s experimental question. While each experiment and question will be defined by students, all experiments will work toward collaboratively answering the question: What effect does the increasing atmospheric CO2 have on the ocean and its subsystems?



Course: Life Science, Integrated Science, STEM, BioChem, Marine Science

Unit: Ocean Acidification, Ecology, Biogeochemical Cycling

See the NGSS buttons in the left-hand panel of this page for an overview of the standards addressed in this lesson.  Also, please see the documents on the Standards Addressed page for all NGSS, WA State (Science, Math and Literacy), and NOAA Ocean Literacy Education Standards connections. In particular, for this lesson, due to the variety of experiments completed within classrooms, students will learn and do a variety of activities. Because each student will complete different labs in this lesson, each student will not complete all of the listed standards.  However, ideally, they will complete 1-2 sets of performance expectations.  To give you a broad, big-picture overview, in addition to the aligned objectives linked above, for this lesson, here is an overview of:

What Students Learn
  • The ocean is an intricate network of abiotic (nonliving) and biotic (living) factors. Research helps us understand and predict changes in this system as well as any reverberating effects.
What Students Do
  • Implement a scientific investigation using appropriate technology, multiple measures, proper controls, systematic data collection and safe approaches.


This lesson requires at least two 50-min periods, though the number of class periods can extend to seven days depending on the goals and scope of the experiments

The purpose of this lesson is to allow students to complete research on the topic of ocean acidification and to work toward answering their interest group’s experimental question.

Advanced Prep

Prior to beginning this lesson, students should have handed in their experimental plan. This should have included a detailed list of materials and equipment.  Many of these items you will need to gather, some will be available in the general lab setting that students will have an opportunity to gather. We have prepared a list of commonly used materials (Word Doc | Google Doc) for your convenience.

Please read this entire lesson plan, including attached documents, before beginning this lesson. Rather than put all information into this main page, we have included detailed, content-specific information in the linked documents.

We recommend students complete their designed experiments.  However, throughout the text and attachments below, you will notice possible lab protocols and procedures that have been provided as a reference to you.  You can also have students follow these procedures as you see fit.

Background Information

These open-source primary papers and information may be useful to you as you familiarize yourself with marine science and specifically diatoms:

These e-Lectures are also specifically helpful.  They were presented in 2016 and can be downloaded here or accessed from the freely available public, online Wiley library, which can be found at: http://aslopubs.onlinelibrary.wiley.com/hub/journal/10.1002/(ISSN)2164-0254/

The materials below have been arranged by topic and contain both teacher and student reference resources.

Lab Techniques

Diatom Labs

Shell Dissolution Labs

General Chemistry Labs Surrounding Biological Questions

  • Teacher Resource – Lab: CO2 and Salinity (Google Doc | Word Doc)
  • Teacher Resource – Lab: CO2 and Temperature (Google Doc | Word Doc)
  • Teacher Resource – Student Data: CO2, Salinity and Temperature (Google Doc | Word Doc)
  • Teacher Resource – Example of Student Work (CO2 and pH Lab) (PDF)
  • Teacher Resource for AP Chemistry Students
    • Laboratory Lesson Plan: Titration to Determine Buffering Capacity (Google Doc | Word Doc)
    • Lab Titration Data Analysis and Calculations (Excel)
    • PowerPoint presentation (Google Slide | PowerPoint) for further background information on Ocean Acidification and Alkalinity, by Hilary Palevsky of UW.
  • Student Resource – Lab: CO2 and Salinity
  • Student Resource – Lab: CO2 and Temperature

Lesson Sequence

Day Prior to Lab Experimentation:  We recommend having students gather the supplies they are able to retrieve (beakers, etc.) and placing them in a bin, to be used on the actual day of experimentation.  You should gather any other supplies as needed and place at the front of the room for students to retrieve.  Remind students that this is collaborative research and they should be respectful of the materials they share.  They should have their lab notebooks completely ready to begin experimentation.  Having a flow chart in their lab book of their exact procedure will help them make the most of their time in the lab.  Generally, all students completed their first day of experimentation in 45 minutes when they were well prepared.

Safety:  Students should be reminded to ALL use proper safety gear and to take appropriate safety precautions.  Though their group’s experiment may not be inherently dangerous, with many experiments happening at the same time, accidents may happen.  For instance, during field testing a group placed 3 grams of dry ice into marine water in a 70 mL plastic culture flask.  They placed the vented top on the flask.  After about 10 seconds, the pressure build up caused the side wall of the flask to explode clear across the room.  Everyone had safety goggles on and all was fine, but it was a great reminder of the powerful force of gas particles.  If needed, you can assign one person in each group to be a safety officer to give reminders to their group members about taking proper precautions and maintaining a safe environment.

  • Two other common “mistakes” during this lesson.
    • Make sure if using a water bath, students understand the difference between Celsius and Farhenheit.  One student group wanted to model their experiment on Caribbean water temperatures.  They turned up the dial on the communal water bath to 80 degrees, thinking it was listed in Farhenheit, though it was not.  This led to near boiling temperatures, melting of plastic containers holding diatoms and upsetting others in the class sharing the equipment.
    • Baking soda and vinegar are commonly used by students as reactants to produce CO2.  Remind students that if using rubber stoppers, they should expect them to violently fly off of the top of their flasks.  They could hold them tightly, though we recommend allowing them to remain loose instead.  They will know they are losing mass.  However, they could use stoichiometry to calculate the approximate amount of gas made and transferred into their vessels.

Student Experimentation

Before beginning lab work, remind students again of the big picture.  While each group has their own question, all questions should lead to the class’ main question:  What effect does the increasing atmospheric CO2 have on the ocean and its subsystems?  Similar to the work happening in laboratories across the world, today they will embark on collaboratively understanding some part of this question.  In your class, they are providing evidence and contributing to replicates.  This is noteworthy because the formation of theory is based on years of proof.  In addition, the building of accurate models, which are needed to make future predictions, result from a large amount and multiple varieties of data.  As they complete this as a class, not only are they working on unanswered questions, but they are also developing an understanding of systems science, systems thinking, and improving their skills of inquiry, problem-solving, and critical thinking.  This lesson is a terrific opportunity for students to practice and develop these important “big skills.” When they get to a rough spot in their experiment, encourage them to engineer and problem-solve together to make it work.  Remind students to ask themselves, “How will I know that I know?  How will I compare the beginning with the end while being certain how I got there?”  Remind them to write everything down, even if it seems unimportant and to have fun.

Managing 8+ Different Experiments in One Classroom:  Some students will have experiments that take a large percentage of class time each day. For instance, for people growing diatoms, counting and recording cells and possibly readjusting CO2 levels will take the majority of class time. However, for someone who is measuring the percent change in mass of coral or shells will be in and out of the lab much more quickly. Because of this, and to continue modeling current research, we have incorporated an online research and data component in this module. Please see Lesson 5b for more details.

You completed Instructional Activities. Please move to Assessment via the Tab located above.


How will I know they know?

  • Completed Lab Investigation, Worksheets and/or Notebook:
    • Were students able to work with their group members and the class at large to answer the main question?
    • Were students able to use experimentation to investigate their question?
    • Were students able to use appropriate technology, multiple measures, proper controls, systematic data collection and safe approaches?
    • Were students able to appropriately discuss observations and conclusions in their lab notebook and/or with their peers?
    • Were students able to appropriately document experimentation, data, and results in their notebook?
    • Were students able to appropriately answer analysis questions?
  • Mini-Surveys:  As part of our effort to ensure quality STEM learning experiences, we invite you to participate in short, but informative surveys. You can complete one, all or any variation between. Here is a downloadable Teacher Overview to guide you through all surveys.
    • A mini-survey is a short survey (1-3 minutes) that students and teachers will use several times over the course of the module. The questions are identical each time, so the same link can be used each time.
    • Student Mini-survey link (https://www.surveymonkey.com/r/OA_StudentSurvey). Please provide 2-4 minutes for students to complete the mini-survey while in class. It should take most students one minute or so, especially after the first survey or two (because the questions remain the same).
      • When prompting students to take this survey at this timepoint (#4), please remind students that this survey covers information taught over the entirety of Lesson 5 (which includes experimentation of 5a, and the supplemental materials found in 5b and 5c.  Here is an example prompt for students: Take this mini-survey while thinking of the lessons we completed on [Tuesday through Friday] that allowed you to:
        • work on your experiment
        • use online data, websites, videos, and
        • use models to further explore and understand OA
      • Please complete the teacher survey while students are taking the mini-survey, or at the end of the day. Please take it on the same day the students take theirs (https://www.surveymonkey.com/r/OA_TeacherSurvey).
    • Here is the entire Survey Teacher Guide that you can use when implementing these surveys.  Thank you!


Since there are so many potential resources to use for this lesson, please see the bulleted list of resources highlighted in blue in the instructions tab for all of the resources needed for this lesson.


Based on student experience and background, provide assistance through arranging groups and assigning experimental protocols as needed.


To help students better understand pigments, such as those produced by diatoms and other photosynthesizers, try this lab submitted by Mike Walker of Olympic High School in Bremerton, WA – Why are plants green? The Monterey Bay Aquarium Research Institute’s Primary Productivity Lab Activity is a useful one that nicely demonstrates the chemical factors needed for phytoplankton growth.


Many teachers and scientists participated in the creation of these lessons and content. Please view the list of credits for this work.