Timber (Updated!)

What size tree should we use for lumber?

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Timber (Updated!)

What size tree should we use for lumber?

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Check it out! This lesson was just updated in September 2024, and we hope you love the new and improved version. If you've already prepped an earlier version, fear not, you can still find those here through Thursday December 5, 2024.

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2023-2024 Versions

In the fall of 2024, Citizen Math released updated versions of every lesson in our library, plus a few new ones! We know you may have already prepped an earlier version or planned a repeat of last year, so we're continuing to make these earlier versions available through Thursday December 5, 2024.

You can find the new lessons through the regular search, and we hope you love them as much as we do. You can read more about these updates in Our Community.

What’s the best strategy for cutting down trees? From building houses to burning charcoal, humans have many different uses for wood. Unfortunately, trees are disappearing in many parts of the world, including the older and larger trees that are so critical to the environment.

In this lesson, student use cylinder volume to determine how the amount of wood in a tree changes as it grows and discuss how communities around the world can harvest (or not harvest) wood in a sustainable way.

REAL WORLD TAKEAWAYS

  • Most houses in the United States are constructed using wood; the lumber used to build houses comes from cutting down trees.
  • Constructing the typical new house in the U.S. requires around 22 large-size trees. If the tree is smaller, more will be needed.
  • Trees provide habitat for birds and animals. They also clean carbon from the air and make the oxygen that humans breath.
  • In terms of wood and carbon, trees become dispoportionally more valuable as they grow; one old tree is “worth” many young trees.
  • While humans have long used trees for worthwhile ends (building homes, boats, etc.), in recent years deforestation has become a problem around the world. Planting small trees to replace clearcut large trees may not be a viable solution.

MATH OBJECTIVES

  • Calculate the volume of a cylinder
  • Understand why the volume of a cylinder increases at a non-constant rate (i.e. why doubling the diameter and height of a cylinder causes its volume to more than double)
  • Solve real world problems using unit rates

Appropriate most times as students are developing conceptual understanding.
Grade 8
Cones, Cylinders, Spheres
Grade 8
Cones, Cylinders, Spheres
Content Standards 8.G.9 Know the formulas for the volumes of cones, cylinders, and spheres and use them to solve real-world and mathematical problems.
Mathematical Practices MP.2 Reason abstractly and quantitatively. MP.3 Construct viable arguments and critique the reasoning of others. MP.4 Model with mathematics. MP.7 Look for and make use of structure.

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