Axle Roads (Updated!)

How do vehicles turn so smoothly?

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Axle Roads (Updated!)

How do vehicles turn so smoothly?

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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.

How do vehicles turn so smoothly? When a car makes a U-turn, the outer wheel travels farther than does the inner wheel. So why doesn’t the car feel jerky?

In this lesson, students calculate the circumferences of circles to determine how far vehicles travel during a turn and explore the engineering that allows cars to turn so smoothly.

REAL WORLD TAKEAWAYS

  • A turning radius describes the smallest circle a car can make. The smaller the radius, the tighter the turn.
  • Left and right car tires have to cover different distances – and thus rotate different numbers of times – when turning. A differential axle allows this to happen.

MATH OBJECTIVES

  • Calculate the circumference of a circle
  • Model with geometry to solve real-world problems

Appropriate most times as students are developing conceptual understanding.
Grade 7
Measuring Circles
Grade 7
Measuring Circles
Content Standards 7.G.4 Know the formulas for the area and circumference of a circle and use them to solve problems; give an informal derivation of the relationship between the circumference and area of a circle.
Mathematical Practices MP.2 Reason abstractly and quantitatively. MP.4 Model with mathematics.

Other Grade 7 Lessons