This section addresses students' tendency to focus on obvious causes. It introduces students to the concept of non-obvious causes. Non-obvious causes are often overlooked when people generate explanations. Air pressure is typically non-obvious, and historically its effects were attributed to other causes.

Section 1 Table of Contents

• Lesson 1: Air Pressure is Non-obvious but Causes Effects
  • Understanding Goals
  • Background Information
  • Lesson Plan
    • Analyze Thinking
    • RECAST Thinking
    • Explore Causality
    • Review, Extend, Apply
• Lesson 2: When Non-obvious Causes Become Obvious
  • Understanding Goals
  • Background Information
  • Lesson Plan
    • Analyze Thinking
    • RECAST Thinking
    • Explore Causality
    • Review, Extend, Apply
• Resources for Section 1
  • Thinking About Hidden or Non-obvious Causes Sheet (PDF: 12 KB / 2 pages / 8½" X 11")
  • The Discovery of Air Pressure: A Brief History Sheet (PDF: 62 KB / 2 pages / 8½" X 11")
• Reinforcement Activities
  • Going to Great Heights (PDF: 21 KB / 1 page / 8½" X 11")
  • Reasoning About Non-obvious Causes (PDF: 13 KB / 2 pages / 8½" X 11")
  • Is Air Pressure Involved? (PDF: 19 KB / 3 pages / 8½" X 11")
• Endnotes for Section 1

Explanation of Photo

What causes a sunset? The cause is non-obvious. When sunlight travels through the atmosphere to Earth, its rays are scattered by the molecules that make up the air. Higher frequencies of light, such as blue and green, are scattered more than lower frequencies, such as red. When the sun is directly overhead, its light travels the shortest distance possible through the atmosphere to an observer on earth, and not much scattering occurs. But at sunrise and sunset, sunlight travels the longest path through the atmosphere to earth, given the sun's position in the sky, and this causes increased scattering, letting only redder frequencies of light reach earth. Particles in the atmosphere, such as air pollution, smoke, or ash from a volcanic eruption, scatter the sunlight even more, resulting in redder and more dramatic sunsets.