Adventure 1 – Introduction and Measuring the World

A stick, a shadow, and a bold idea—see how Eratosthenes who lived more than two thousand years ago measured the circumference of Earth. One clever observation turns into a result that feels almost impossible. It’s a great example of how we can use simple local information to understand something big. You’ll see how the idea of a small angle and a known distance can unlock the size of our entire planet.

• 🌍 Measure the World — Adventure

In this activity you use a small angle and a known distance to estimate Earth’s circumference. You are doing with shadows and circles what we will later do with areas and slopes: using simple local information to understand something big.

Next, watch 3Blue1Brown — The Essence of Calculus (Chapter 1)

This video shows how we can understand change by looking at slopes of curves, and also how the area of a circle can be found by building it from many thin slices. It introduces the idea that even smooth motion can be measured moment by moment. Focus on how curves reveal both changing motion and accumulated area.

• 🧩 Open: Activities 1 & 2 — Student Worksheet Page

• Worksheet A — Area Under a Line
• Worksheet B — Tangent & Slope