A view into the Phillipine Coral Reef tank at the Academy.

While we use this demonstration in an on-site museum program for 3rd grade school groups, the activity can easily be adapted for your own classroom, aquarium, or science center!

About This Demonstration

Essential Question: How can we protect coral reefs from harm?

Duration: 10-20 minutes

Age Level: We designed this activity as a component of a longer classroom program for 3rd graders, but it can be tailored for conversations with older students, and even adults!

Preparing the Demonstration Materials
Color-changing coral in an aquarium tank for a science demonstration.

Note that making these materials can also be a learning experience for students.

Design the coral models

  1. We used sketchfab.com to 3d print our coral models. Alternatively, coral models could be created by hand using Sculpey Clay.
  2. Mix thermochromic powder (available in a variety of colors) into a white multi-surface base paint and apply two coats:

Prepare your normal and "warmer" ocean environments

  1. Find two fish bowls, plastic containers, or small aquarium tanks.
  2. Heat a thermos-full of water so that it is at least 88° F (boiling water is 212° F, and room temperature water is 70° F).
  3. Fill one bowl with room-temperature water, and the other the heated water.
  4. You may choose to label the bowls. We use the terms "not too hot and not too cold" for the room-temperature water, and "too warm" for the heated water.
  5. Start with the coral in the room-temperature bowl, where they appear colorful and healthy.


Set the Stage by Framing the Discussion

Why Do We Care?

Thriving coral reefs provide billions of people with food, protect our coastlines from storms, provide habitat for one quarter of all life in our oceans, and they are a vibrant place to explore!

We have a responsibility to protect these wonderful habitats from harm and it turns out they need help now!

Impact Story:

When we burn fossil fuels such as coal, oil and natural gas, we release carbon dioxide into the atmosphere. Unfortunately, this carbon dioxide acts like a thickening of a heat-trapping blanket that encircles our earth. As we burn more fossil fuels, we release more carbon dioxide and that heat-trapping blanket gets even thicker, our planet gets warmer, and so do our ocean waters.

In normal times, coral has a relationship with tiny colorful algae that lives in its tissues. The coral provides a home, and the algae (zooxanthellae) makes food which it shares with the coral.

Warming ocean water stresses the coral and stresses the special relationship that coral has with its algae. When oceans warm, coral expels the zooxanthellae from its tissues.Look at the colorful coral pieces in your model ocean. What do you think will happen to this colorful coral if the water gets warm? This is just a model – we would never harm real coral - we want to protect it! So do an experiment - Give it a try!

  1. Move the color-changing coral to a bowl of warm water, where the students will see the impact, and observe “bleaching”.
  2. The color changing coral can be used to connect the concepts that our use of fossil fuels is warming oceans, and that warming oceans result in coral bleaching.
  3. As you facilitate the discussion, move quickly to community solutions, and how we can help protect coral, even though we live miles away from coral reefs.
  4. After discussing these solutions, the coral can be returned from the warm “ocean bowl” to the original cooler bowl or tank, and the coral color will return. This emphasizes the point that it is not too late to act.

What can kids do?

Kids can increase their impact by joining with other kids on Walk & Roll to School Days, or joining a regularly scheduled “Walking School Bus”. Visit the Safe Routes Partnerships website to find examples for your region.

With their caregivers they can learn how much of their home’s electricity comes from clean energy sources (like wind and solar). If you live in San Francisco, check out CleanPowerSF. 

They may be able to check out a Watt-Meter from a public library and learn which devices use the most electricity in their home or school. In San Francisco, this program is known as What's Your Watt.

Kids can talk with teachers, caregivers and friends about ways to reduce the excess carbon dioxide we are putting into our air!

Teacher Background

Can’t plants take care of the CO2?
People are releasing CO2 at levels far higher than the regular levels produced by any natural processes involving plants, animals, air, or water. While regular levels of CO2 stay constant over hundreds of thousands of years, rampant CO2 builds up through our burning of fossil fuels, like coal, oil and natural gas. We call this rampant CO2 because there is too much of it and it is out of control. It builds up too quickly for natural processes to balance it out. This rampant CO2 acts as though it is thickening a heat-trapping blanket around our Earth, causing our planet and our oceans to get warmer.

Is the bleached coral dead?
The bleached coral isn’t dead, but it is sick and hungry and if conditions don’t change, the coral can die. Fortunately, we know that by collectively acting to reduce rampant CO2 emission that comes from the burning of fossil fuels, we can actively reduce the risk to coral reefs, and safeguard the entire interconnected ocean system that supports people and ecosystems around our Earth.

What can we do to help?
The key to getting the climate system back to functioning the way it should is to get away from fossil fuels for energy. This means moving towards clean energy sources, such as wind and solar. These sources don’t add to that heat-trapping blanket effect! Here in California, as a state, we are moving in a stepwise manner towards having our energy sector produce at least a third of our electricity from sources other than fossil fuels. We are proud that the city of San Francisco is also a leader in reducing the use of fossil fuels. Thanks to an environmentally engaged community, the city launched CleanPowerSF, which now provides 48% clean energy to all San Francisco homes, with the option of upgrading to 100% renewable energy! Many other California cities offer similar choices. We can support this in our own communities by staying informed of the options available to us, and by choosing clean energy when available. As we talk about it with each other, with landlords, and with civic leaders, we will make it clear that we expect clean energy delivered to our homes! By changing how we get our energy, we can protect ecosystems near and far, including our amazing coral reefs!

Recommended Resources

Take a free on-line course on researched approaches for talking about climate change through the National Network for Ocean and Climate Change Interpretation (NNOCCI).

Search bioGraphic for illuminating videos and articles related to climate impacts on coral.

Appropriate for: 3rd Grade - 6th Grade
Prep Time: 60 minutes
Activity Time: 20 minutes
Subjects: Life Science

Attached Files