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Benedicte Kurzen/NOOR/Redux (Nursery)
Math,

Stopping the Sahara

Several African nations team up to fight climate change

By Jeanette Ferrara
From the April 2021 Issue

Learning Objective: Students will partition shapes into fractions representing plots of farmland in the Sahara desert.

Lexile: 890L; 740L
Focus Area: Geometry,
Standards
  • MATHEMATICAL PRACTICES: MP6, MP7 CCSS: 3.NF.A.1, MP4 TEKS: TEKS: 3.3E

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Lexile® measure

  • 890L
  • 740L

Benedicte Kurzen/NOOR/Redux (Nursery)

Young trees in Senegal will be distributed as part of the Great Green Wall project.

In 2007, 11 African countries made a pact. They would work together to create something that became known as the Great Green Wall—a wall of trees that stretches across sub-Saharan Africa. 

The project aims to block the spread of the Sahara by planting trees and other plants. The desert—already one of the largest in the world—has become 10 percent bigger in the past hundred years. It’s grown because climate change is making the region hotter and drier than ever.

Eleven African countries made a pact in 2007. They decided to work together to create the Great Green Wall (GGW). The Great Green Wall is a wall of trees. It stretches across sub-Saharan Africa.

The goal of the Great Green Wall project is to stop the spread of the Sahara Desert. The plan is to plant trees and other plants along the desert’s border. The Sahara is one of the largest deserts in the world. It has grown 10 percent bigger in the past hundred years. That growth is because of climate change. Climate change is making the area hotter and drier than it has ever been.

“The Great Green Wall is Africa’s major contribution to the global fight against climate change,” explains Chris Reij of the World Resources Institute. He monitors the project. “The original goal was to reclaim 30 million acres from the desert.” That’s about the size of the state of Pennsylvania.

About 15 percent of the work has been completed so far. In the meantime, the project has grown even bigger. Ten more African countries have joined (see map). 

“The Great Green Wall is Africa’s major contribution to the global fight against climate change,” explains Chris Reij of the World Resources Institute. Reij monitors the project. “The original goal was to reclaim 30 million acres from the desert.” That’s about the size of the state of Pennsylvania.

About 15 percent of the work has been done so far. The project has grown bigger since its start. Ten more African countries have joined (see map).

Jane Hahn/Redux (Teen)

A teen in Senegal waters a garden of saplings for the Great Green Wall.

“Now, the goal is to restore 247 million acres of land by 2030,” Reij says. That’s about the size of California, Montana, and Nebraska combined!

Participating countries focus on replanting forests and restoring degraded land. That way farmers can grow crops more successfully.

Their efforts are already paying off. The project is helping fight climate change, push back the desert, provide jobs, and increase food production. 

Once complete, the Great Green Wall will be three times larger than Australia’s Great Barrier Reef!

“Now, the goal is to restore 247 million acres of land by 2030,” Reij says. That’s about the size of California, Montana, and Nebraska combined!

The countries that are a part of the project are planting forests. They are also working to fix land that was taken over by the desert. They are making it so that plants can grow on the land again. That way, farmers are better able to grow crops.

The work these countries are doing is already changing the land. The Great Green Wall project is helping fight climate change. It is helping to push back the desert. It is giving people jobs. It is also increasing the amount of food the countries can grow.

The Great Green Wall will be three times larger than Australia’s Great Barrier Reef when it’s finished!

Math Talk

What are some ways you can compare land areas? 

Math Talk

What are some ways you can compare land areas? 

Partition Shapes

What to Do

Many shapes can be partitioned, or equally divided into a number of parts. These parts each represent a fraction of the total area of the shape.

Example

A sub-Saharan farmer divides a rectangular plot of land into4 equal parts. He will plant trees on 3 parts and farm crops on 1 part. What fraction of the land will have trees planted on it?

• We can divide his land into 4 equal parts. This is our denominator. Label the parts used for trees and farming.

• Determine what fraction of the farmer’s land will be dedicated to planting trees. Since 3 parts will have trees, this is our numerator.

So 3/4 of the farmer’s land will be dedicated to planting trees.

Partition Shapes

What to Do

Many shapes can be partitioned, or equally divided into a number of parts. These parts each represent a fraction of the total area of the shape.

Example

A sub-Saharan farmer divides a rectangular plot of land into4 equal parts. He will plant trees on 3 parts and farm crops on 1 part. What fraction of the land will have trees planted on it?

• We can divide his land into 4 equal parts. This is our denominator. Label the parts used for trees and farming.

• Determine what fraction of the farmer’s land will be dedicated to planting trees. Since 3 parts will have trees, this is our numerator.

So 3/4 of the farmer’s land will be dedicated to planting trees.

Now You Try It

Answer the questions on partitioning shapes on a separate sheet of paper.

Answer the questions on partitioning shapes on a separate sheet of paper.

Jim McMahon/Mapman® (Map)

A. A farmer in Senegal has 5 acres of land in a rectangular plot. He wants to plant trees on 4 acres and crops on 1 acre. Draw the farmer’s land.

A. A farmer in Senegal has 5 acres of land in a rectangular plot. He wants to plant trees on 4 acres and crops on 1 acre. Draw the farmer’s land.

B. Shade the parts of the land that will have trees.

B. Shade the parts of the land that will have trees.

C. What fraction of the farmer’s land will have trees planted on it?

C. What fraction of the farmer’s land will have trees planted on it?

A. A farmer in Chad has 8 acres of land in a large circular plot. She wants to reforest 2 of those acres. Draw the farmer’s land.

A. A farmer in Chad has 8 acres of land in a large circular plot. She wants to reforest 2 of those acres. Draw the farmer’s land.

B. Shade the parts of the land that will be reforested with trees.

B. Shade the parts of the land that will be reforested with trees.

C. What fraction of the farmer’s land will have trees planted on it?

C. What fraction of the farmer’s land will have trees planted on it?

A. A farmer in Cameroon has 9 acres of land in a square plot. She wants to restore 3 of those acres with trees. Draw the farmer’s land.

A. A farmer in Cameroon has 9 acres of land in a square plot. She wants to restore 3 of those acres with trees. Draw the farmer’s land.

B. Shade the parts of the land that will be restored.

B. Shade the parts of the land that will be restored.

C. What fraction of the farmer’s land will be restored?

C. What fraction of the farmer’s land will be restored?

Which farmer from the previous questions has the greatest fraction of land that will be restored with trees? 

Which farmer from the previous questions has the greatest fraction of land that will be restored with trees? 

Continue Your Learning

  • Watch the video “The Great Green Wall” (above). Create a poster advertising the project using at least 3 number facts you learned from the video.
  • Draw a rectangle, circle, or square. Then roll a die twice, recording the number after each roll. The greater number will be your denominator, and the other number will be your numerator (If you roll a pair, that’s OK!). Divide your shape evenly according to the denominator you rolled. Then shade in the parts to represent your numerator. What fraction, or whole number, does your shading represent? Repeat 3 more times!

Continue Your Learning

  • Watch the video “The Great Green Wall” (above). Create a poster advertising the project using at least 3 number facts you learned from the video.
  • Draw a rectangle, circle, or square. Then roll a die twice, recording the number after each roll. The greater number will be your denominator, and the other number will be your numerator (If you roll a pair, that’s OK!). Divide your shape evenly according to the denominator you rolled. Then shade in the parts to represent your numerator. What fraction, or whole number, does your shading represent? Repeat 3 more times!
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