This section addresses students' tendency to think of pressure as a force that actively pushes and is unidirectional. Students are encouraged to think about pressure as a passive cause that is omnidirectional.

Section 2 Table of Contents

• Lesson 3: Passive Causal Agents and the Omnidirectional Nature of Air Pressure
  • Understanding Goals
  • Background Information
  • Lesson Plan
    • Analyze Thinking
    • RECAST Thinking
    • Explore Causality
    • Review, Extend, Apply
• Lesson 4: Considering How Well Models Depict Air Pressure as Omnidirectional
  • Understanding Goals
  • Background Information
  • Lesson Plan
    • Analyze Thinking
    • RECAST Thinking
    • Explore Causality
    • Review, Extend, Apply
• Resources for Section 2
• Reinforcement Activities
  • Water in a Straw (PDF: 51 KB / 2 pages / 8½" X 11")
  • Water in a Cup (PDF: 76 KB / 2 pages / 8½" X 11")
  • Why Does the Top Fly Off of the Teapot? (PDF: 56 KB / 1 page / 8½" X 11")
  • The Squished Cup: Is Water Pressure Unidirectional or Omnidirectional? (PDF: 37 KB / 1 page / 8½" X 11")
• Endnotes for Section 2

Explanation of Photo

What makes an arch bridge stay up? It can be described as a form of passive causality. The distribution of weight and the balance of forces results in the bridge staying up. We don't notice anything actively happening to keep the bridge up, but if the balance was disturbed, we would quickly realize how it caused the bridge to stand.