Teaching Sequence

Work through this resource material in the following sequence:

05 minutes	Part A: Activating prior knowledge about blue carbon and ratios
15 minutes	Part B: Explicit Teaching - How to use ratios to compare blue and green carbon sequestration
25 minutes	Part C: Independent task - Use ratios to compare blue and green carbon sequestration
05 minutes	Reflection

Part A: Activating prior knowledge about blue carbon and ratios

Step 1.

Discuss:

What are some natural methods you know of sequestering carbon from the atmosphere?

You may need to define sequestration as the chemical process of taking carbon out of the air and storing it physically in some way.

Students are probably going to go to the most obvious option first: trees.

However, can they name any others?

Step 2.

Explain: Blue carbon is carbon sequestration (the removal of carbon dioxide from the earth's atmosphere) by the world's oceanic and coastal ecosystems, mostly by algae, seagrasses, macroalgae, mangroves, salt marshes and other plants in coastal wetlands. These are sometimes referred to as 'blue forests' in contrast to land-based 'green forests'.

Step 3.

Discuss:

Can you define or explain the term 'ratio'? Can you give an example from real life?

Students might focus on the number of males compared to the number of females in class.

Step 4.

Explain: A 'ratio' is defined as the relation between two amounts showing the number of times one value contains or is contained within the other.

Part B: Explicit Teaching - How to use ratios to compare blue and green carbon sequestration

Step 1.

Explain: One of the great things about blue carbon that is exciting climate scientists is its extreme efficiency.

Mangroves and salt marshes remove carbon from the atmosphere at a rate 10 times greater than tropical forests like the amazon.

They also store three to five times more carbon per acre than tropical forests.

You might like to keep these figures on the board for later reference.

Step 2.

Let's explore this in more detail.

Discuss:

If we had 1 acre of mangroves, how many acres of tropical forests would we need to store the same amount of carbon emissions? 3 or 5 (Let's say 5, as it's an easy number to work with.)
How could you represent this as a ratio? 1:5.
Can you create a visual representation of this ratio? Students could use circles and squares if they wanted to, so long as it looked something like this:

How many hours would it take a tropical forest to sequester the same amount of carbon as an area of mangroves? 10 hours for the forest and 1 hour for the mangroves.
How could you represent this as a ratio? 10:1.
Can you create a visual representation of this ratio?

Step 3.

We can find practical, real-world numbers to compare by simply multiplying by the ratio.

If we had 4 acre of mangroves, how many acres of tropical forests would we need to store the same amount of carbon emissions? 20.
How could you represent this as a ratio? 4:20. 1 x 4 = 4. 5 x 4 = 20.

Step 4.

Remember that a ratio can simplified, just like fractions.

How could you represent this as a ratio? 4:20. This is the same as 1:5 because 4 divided by 4 is 1 and 20 divided by 4 is 5.

Part C: Independent task - Use ratios to compare blue and green carbon sequestration

Step 1.

Distribute the Student Worksheet to students, and support them in working through the questions. The answers are below for your reference.

PART A

1. 1:3

2. 5:15

3. 4.5:13.5

PART B

1. 17:170

2. 41.25:412.5

3. 9.06:90.6

PART C

1. 1:999

2. If there was 1m²of segrass on the ocean floor, there would be 999m²of other material on the ocean floor.

3. Students could use any value between 10 and 18. One answer would be 10:90 or 1:9.

PART D

1. 3:5

Teacher Reflection

Take this opportunity to reflect on your own teaching

What did you learn about your teaching today?
What worked well?
What didn’t work so well?
What would you share?
Where to next?
How are you going to get there?

IPCC - Blue Carbon

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