Implement this lesson:
After students have begun to learn about the damage OA has on shell creating organisms
Learning objective:
Students will be able to understand the impacts of acidified seawater on mussels and oyster shells. Students will run experiments exposing shells with seawater at different levels of acidity representing current and potential future ocean conditions.
Next Generation Science Standards (NGSS)
Common Core ELA Standards
Informational Text Grades 4-8:
1 – Refer to details and examples in a text when explaining what the text says explicitly and when drawing inferences from the text 4 – Determine the meaning of general academic and domain-specific words or phrases in a text 7 – Interpret information presented visually, orally, or quantitatively and explain how the information contributes to an understanding of the text in which it appears.
Writing Standards Grades 4-8:
1 – Write opinion pieces on topics or texts, supporting a point of view with reasons and information 2 – Write informative/explanatory texts to examine a topic and convey ideas and information clearly 4 – Produce clear and coherent writing in which the development and organization are appropriate to task, purpose, and audience
Common Core Math Standards
Mathematical Practices: Construct viable argument and critique the reasoning of others Attend to precision Measurement and Data Grades 4-5 Represent and interpret data
Next Generation Science Standards
4 Structure, Function, and Information Processing 4-LS1-1 Construct an argument that plants and animals have internal and external structures that function to support survival, growth, behavior, and reproduction
Science and Engineering Practices: Engaging in Argument from Evidence
Crosscutting Concepts:
Cause and Effect Systems and System Models 3-5 Engineering Design 3-5ETS1-2 Generate and compare multiple possible solutions to a problem based on how well each is likely to meet the criteria and constraints of the problem.
Science and Engineering Practices Constructing Explanations and Designing Solutions
Crosscutting Concepts:
Influence of Science, Engineering, and Technology on Society and the Natural World MS Human Impacts MS-ESS3-3 Apply scientific principles to design a method for monitoring and minimizing a human impact on the environment
Science and Engineering Practices: Constructing Explanations and Designing Solutions
Crosscutting Concepts:
Cause and Effect Influence of Science, Engineering, and Technology on Society and the Natural World
Texas Essential Knowledge and Skills (TEKS)
K.6A use the senses to explore different forms of energy such as light, thermal, and sound
K.9B examine evidence that living organisms have basic needs such as food, water, and shelter for animals and air, water, nutrients, sunlight, and space for plants
K10B identify basic parts of plants and animals
1.6(A) identify and discuss how different forms of energy such as light, thermal, and sound are important to everyday life
1.10(A) investigate how the external characteristics of an animal are related to where it lives, how it moves, and what it eats
2.9(A) identify the basic needs of plants and animals
2.9(B) identify factors in the environment, including temperature and precipitation, that affect growth and behavior such as migration, hibernation, and dormancy of living things
2.9(C) compare the ways living organisms depend on each other and on their environments such as through food chains
3.9(A) observe and describe the physical characteristics of environments and how they support populations and communities of plants and animals within an ecosystem
5.9(A) observe the way organisms live and survive in their ecosystem by interacting with the living and nonliving components.
5.9(B) describe the flow of energy within a food web, including the roles of the sun, producers, consumers, and decomposers
5.9(C) predict the effects of changes in ecosystems caused by living organisms including humans, such as the overpopulation of grazers or the building of highways
5.9(D) identify fossils as evidence of past living organisms and the nature of the environment at the time using models
Overview
The burning of fossil fuels for energy production, manufacturing, and transportation has driven the level of carbon dioxide in the atmosphere to levels 30% greater than prior to the industrial revolution. Higher atmospheric levels of carbon dioxide have resulted in increasing amounts of carbon dioxide dissolving in the ocean leading to the reduction in pH or increase in acidity of the ocean, also known as “ocean acidification”. It should be noted that the ocean is not acidic (pH<7) however the trend in declining pH has been observed and is referred to as “ocean acidification”. As shown in the chemical formulas in this illustration, when carbon dioxide (CO2) dissolves in seawater, it creates carbonic acid, which releases bicarbonate ions (HCO3-) and hydrogen (H+) ions into the water. The hydrogen ions make the seawater more acidic (lowering its pH). In addition, some of the hydrogen ions react with carbonate ions (CO3=) already in the seawater to create more bicarbonate. This reduces the amount of carbonate (an important mineral for building shells) dissolved in the seawater.The impacts of ocean acidification and lower carbonate ion concentrations on marine ecosystems include reduced growth of organisms that form calcareous skeletons or shells, such as corals, pteropods (swimming snails) and bivalves (such as oysters, clams and mussels). Since the beginning of the industrial revolution, about one third of the CO2 released by human activities has been absorbed by the world’s ocean which plays a key role in moderating climate change. Without the ocean absorbing CO2, the CO2 in the atmosphere would be much higher, potentially increasing the effects of global climate change.
Materials:
- sodastream carbonator (forces CO2 into the water)
- pH meter
- Seawater
- Glass jars with airtight lids
- Digital Scale
- Shells
Advanced Prep:
- print the pdf https://drive.google.com/file/d/14R3E2KpO2RVjDXamMW4QG4_GvkhR0dHY/view?usp=sharing
- Review effects of acids and bases on oysters shells using a microscope https://docs.google.com/presentation/d/19ImfY80agilDZtVto-UgQ-fL4qX-0JuadaqW6XQXHsk/edit?usp=sharing
Procedure:
- Have students weigh each shell and record this mass as the initial mass at the beginning of the experiment.
- Using a calibrated pH meter, measure pH of the seawater and have students record the number in their lab notebooks
- Use the Sodastream to carbonate (acidify) one liter of sea water (3 pumps)
- Measure pH of carbonated seawater using a calibrated pH meter and have students record that number in their notebooks
- Pour regular (non-carbonated) seawater into glass jars (one for each student) with sealing lids.
- Have students determine an approximate pH level where they would like to do their experiment. Make sure you reserve two shells to put in a jar with the regular noncarbonated seawater as your “control”. Ask students why this is important.
- Mix a small amount of acidic sea water (use an eyedropper and have students record the number of drops to get their desired pH). Keep the acidified sea water in a 1 liter bottle. Make sure to stir the seawater well and continue to add acidified seawater if needed. You can also put in a few drops of bromothymol blue (a pH indicator) to see a color change as you add the acidified water.
- Try to get a range of numbers from about pH 5 to pH 7.8. 10) You may want to have pairs of students work together so several students use the same water to run their experiments so you have replicates. Remember to fill the jars to the top (with a very small amount of space so you can put the shell in without overflowing) and measure pH before you seal them.
- Have students label jars with their names and record the starting pH in their notebooks
- Drop a shell into the seawater and seal the lid. Ensure there is no air space at the top.
- After one week have students measure pH and remove shells and dry them overnight.
- If there has been a change of more than 0.1 pH unit, change out the water and fill jar with pH of the same value as the starting experiment. Have them look up the number of drops they used of the acidified water and repeat using that same number of drops. Record pH at start of second week in lab notebook.
- After shells are dry, ask students to weigh shells and record mass.
- Place shells back into jars with water at selected pH. Repeat data collection (weighing dry shells) every week for four weeks.
- Calculate the percent weight change [(ending weight – beginning weight)/beginning weight X 100]
- Create a line graph showing the data
Variation: Complete the same lab except use varying amounts of vinegar instead of a sodastream.
Questions to Ask:
Pre-experiment
- What are some acidic items around your house? Can you rank them in order of most acidic to least?
- What is more basic/acidic freshwater or saltwater?
- What is your hypothesis for what will happen?
Post-experiment
- Did your results support your hypothesis?
- Did the results surprise you? Why?
- How does this investigation demonstrate the effect of ocean acidification on shells?
Extensions:
– Have students read Earth’s Acid Test published in Nature March 10, 2011 and answer questions about the text.
– Have students participate in the International Student Carbon Footprint Challenge (http://footprint.stanford.edu/calculate.html). Students will investigate how to calculate their own carbon footprint and develop and present ideas on how they individually, as a family, and as a school community can lower their carbon footprint and help decrease the amount of CO2 (produced by the burning of fossil fuels) being absorbed by the world’s oceans. Have students present and compare their solutions to reduction of carbon footprint and have them use individual plans to come up with the best overall plan. For middle and high school students have students devise a way to evaluate the effectiveness of their solution(s).
Evaluation:
-Produce a presentation (oral, graphic/technological) representing the results of the experiment. Include theories as to why these results are important and what it could mean to the marine environment and animals with a calcium carbonate shell. Have students (individually or as a class) develop a solution to the problem of increasing ocean acidity. Have them compare different ideas and evaluate the effectiveness of differing solutions.
