Educator Spotlight: Using Math to Tackle Trash

Febriandrini Kumala’s eighth-grade math students applied their knowledge of 3-D shapes to design and build trash cans for their school. Students also developed greater awareness about plastic waste issues.

Febriandrini Kumala is an eighth-grade math teacher at Lazuardi Al Falah Junior High School in Depok, West Java, Indonesia. Photo by Febriandrini Kumala

Your students designed and built trash cans for your school. What was the inspiration for this project?

Our school building is a part of a community learning and sports center. Many people come to the building complex during the weekend to learn English, practice sports, or just hang out in our outdoor cafes. Therefore, every Monday, there is a lot of garbage strewn about and overflowing from the bins.

I asked my eighth-grade students to examine this problem. We conducted a waste audit and concluded that the trash bins were inadequate. However, trash bins are quite expensive. With the small budget we had, we decided to create bins using PVC pipe and wire mesh. Our goal was that the project would yield several more bins for our school. Students were motivated to use their mathematical knowledge to solve this problem.

Students used 3-D modeling software to design trash bins. Photo by Febriandrini Kumala

How did this project impact students?

This project was a new learning experience for all my students. Studying 3-D shapes usually involves pen-and-paper exercises to calculate volume and surface area. For this project, students needed to apply their mathematical knowledge to create an actual 80-liter trash bin from wire mesh and a four-meter PVC pipe. Every group came up with their own unique design for their trash bin.

The project also helped develop students’ empathy for the world they live in. By identifying and working to solve a problem, students recognized their ability to contribute to a better world. They now know they can create change within their community and make an ecological legacy.

What long-term effects has this project had on your students and the school community as a whole?

The long-term effects of this project have been significant. My students have seen their learning benefiting the community, and I hope they feel appreciated. Since completing the project, my students have not been afraid to put forward their ideas and take action. The school community has been a great supporter of this trash bin project. A new policy regarding plastic packaging has been released to the school’s food vendors in an effort to reduce plastic waste.

Students built trash bins using PVC pipes and wire mesh.
Photo by Febriandrini Kumala

Educators: Download full lesson plan here

How did you help students work effectively in small groups?

I encouraged students to ensure that all members of each group were involved, including those with special needs. Everyone had to contribute to the project, no matter how small the contribution. Of course, since my students are teenagers, there is sometimes drama involved in group work. When that cropped up during this project, I told my students that the project was to benefit the community, and they needed to put aside the drama and work well together. They were able to overcome their problems and finish their projects.

How has this project influenced how you teach math?

My teaching philosophy has always been centered around incorporating real-world context into mathematical concepts. Using the National Geographic Learning Framework, I have created a more meaningful mathematics class. I do not just teach mathematics procedures; I give students insights to help them see beyond the numbers and symbols. I also show them that mathematics can solve real problems and provide benefits to their community.

This interview has been edited and condensed.

Interested in joining Febriandrini as a National Geographic Certified Educator? Learn more at

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