Lego Calcification Challenge

Grab your legos and make some molecules

Click to watch video on how to teach lesson

Implement this lesson:

Before or after completing the Calcifiers vs. Non-Calcifiers lesson plan.

Learning objective:

The purpose of this activity is to convey how ocean acidification (OA) affects marine calcifiers’ ability to build their CaCO3 structures (e.g., shells, skeletons, etc.). OA reduces the availability of carbonate ion “building blocks” and therefore reduces the rate of CaCO3 production.

Next Generation Science Standards (NGSS)

Common Core ELA

Standards

Informational Text Grades 4-8:

Refer to details and examples in a text when explaining what the text says explicitly and when drawing inferences from the text.
Determine the meaning of general academic and domain-specific words or phrases in a text.
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:

Write opinion pieces on topics or texts, supporting a point of view with reasons and information.
Write informative/explanatory texts to examine a topic and convey ideas and information clearly.
Produce clear and coherent writing in which the development and organization are appropriate to task, purpose, and audience.

Common Core Math

Mathematical Practices:

Standards

Reason abstractly and quantitatively

Construct viable arguments

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 increase of carbon output is affecting not only our atmosphere, but our ocean as well. The ocean is sometimes referred to as a carbon sink, a helpful buffer against global climate change. In fact, the ocean absorbs approximately 1/3 of all CO2 emissions. However, once dissolved in the ocean, CO₂ still makes a significant impact. It binds to water molecules to produce carbonic acid (H₂CO₃), which can then disassociate into H+ and HCO₃ (bicarbonate).

CO₂ + H₂O H₂CO₃ H+ + HCO₃.

So, what does this mean? More H+ ions mean a lower pH, or, in other words, a more acidic ocean. pH is measured by the number of H+ ions present in a solution and can range from 1-14, with 1 being the most acidic and 14 being alkaline (basic). Distilled water is neutral, with a pH of 7.0. In pre-industrial times, ocean water had a pH of 8.2. Today, the ocean’s pH is 8.0, and it is projected that if we maintain our current CO₂ emissions, pH will drop to 7.7 by the year 2100. If that does not seem overly drastic, consider this: a drop of one pH unit represents a 10-fold increase in acidic H+ ions. An increase in H+ ions creates two problems.

Not only is the ocean’s pH dropping, which can cause the corrosion of the shells and skeletons of many marine animals, such as snails and corals, but the extra H+ ions also tie up carbonate (CO₃). When available, carbonate can combine with calcium to form calcium carbonate (CaCO₃), an important compound used by many organisms as a building material for their shells and skeletons. Currently, coralline algae, corals, some species of snails, and many important planktonic species are being affected by the reduced availability of this important building compound. As corals and coralline algae disappear, so do the many marine animals that rely on them for habitat. While we can talk definitely about the effects of more acidic water and less available calcium carbonate on certain species, we also know that the repercussions of dissolved CO₂ in our ocean do not end there. A change in pH can affect respiration and reproduction. It can cause stress to organisms, and affects the nitrogen cycle. Most aquatic species are adapted to a specific range of pH, and the current anthropogenic change is happening more rapidly than any natural flux ever has, including a low pH interval some 55 million years ago, known as the Paleocene-Eocene Thermal Maximum, which caused a major marine die off. The effects of our carbon emissions on the ocean will therefore be amplified by the simple fact that organisms do not have time to evolve with the change.

Materials:

Legos (2 colors/ sizes)
2 Tupperware bins (shallow rectangular ones work well)
2 Lego base plates (optional)
Audio player (e.g., computer, smartphone)/or stop watch
Art Supplies for labels and signs (e.g., markers, poster board, construction paper)

Advanced Prep:

In two large Tupperware bins, place an equal number (~500) of the smaller Legos:
- One bin represents the ocean today while the other represents the ocean in a high-CO₂ future.
- Each bin contains the same number of smaller Legos, which represent calcium ions, because rising levels of CO₂ do not directly affect ocean Ca²⁺ concentration.
Put 1⁄3 to 1⁄4 of the (~100 total) larger, CO₃^2- Legos into the “Future Ocean” and the remainder into the “Today Ocean.” Note: these ion concentrations are exaggerated for the purpose of illustrating the impact on calcifying organisms.
Label each ocean Example: “Today” and “Future” or “High CO2”

Procedure:

Briefly explain how corals need Ca²⁺ and CO₃²– in order to construct their CaCO₃ skeletons but that elevated levels of CO₂ in the atmosphere and ocean results in a reduced amount of CO₃²– building blocks. Note: More information regarding ocean carbonate chemistry may or may not be appropriate depending on the age/ interest level of the group.
Divide the group into two teams, one for each ocean. Each team will send one member up to their ocean at a time. With their eyes closed, this team member will locate and put together one Ca²⁺ and one CO₃²– Lego. At this point they can open their eyes, return to their team and add their unit of CaCO3 to their reef (if using them, the Lego base plate acts as the sea floor).
Once a team member returns, the next team member goes up to their ocean and repeats the process.
You can conduct this similar to musical chairs, the replay beings and ends with a song
When the song/relay/time ends, have the teams count and report the number of CaCO3 units in their reef (usually just count the number of one color Lego).
Which team has the most CaCO3? Why? If desired, repeat the game a few times and switch up the teams.

Alternative Procedure

The entire team can sit around its respective ocean and all students can put together “CaCO₃” at the same time. This generally works better because all students are participating at once rather than one at a time. However, the carbonate ion Legos get used up much more quickly and probably won’t last for the duration of a song; best to shorten the time for the activity so participants are not left with the impression that the ocean will run out of CO₃^2- completely!

Photos by NOAA Ocean Acidification

Questions to Ask:

Pre-experiment

How can we model chemical reaction?
What chemicals do shell building animals need?
How is ocean acidification affecting shell building animals?

Post-experiment

Which team has the most CaCO3? Why?

Extensions:

Comparing/ contrasting with the real world: In reality, it takes many years, decades and even centuries for corals to reach their full size and build extensive reef systems. We have also exaggerated the difference between present and future carbonate ion concentrations. In reality, the difference is much smaller but because corals are building their skeletons all the time and over longer time frames, the impact eventually shows.
Reefs are made of many different types of corals; corals are colonies made of many individuals: Each team member contributed to building the CaCO3 reef, which is exactly what happens on a reef; not only are there many different types of corals on a reef (e.g., brain corals, branching corals) and calcifying organisms (e.g., calcareous algae), but each coral is made up of many individual-yet-connected little anemone-like polyps that contribute to building the coral’s CaCO3 structure.
Variability among coral organisms and reef systems: Not all corals respond the same way to OA. While some are highly sensitive others seem unaffected. Each team member may have a different approach to locating and putting together their pieces of CaCO3. The amount of reef each team was able to build was due not only to the availability of each ion building block but also how each team member approached the task of “calcification”.

Evaluation:

Compare the two oceans?

a) How many calcium carbonate pieces were you able to put together to build your shell/skeleton in the different oceans?
b) Which ocean was it easier to find the building blocks of your shell/skeleton?
c) In which ocean were you able to put together your building blocks more quickly?
d) The time lost in searching for carbonate ions instead of bicarbonate.
e) If you were a ________, which ocean would you rather live in or would it be easier to build your shell/skeleton in?
f) What can we/you as humans do to help ocean creatures be able to build shells/and skeleton/homes more easily?