This section introduces a puzzle about density—that it is non-obvious. Density is an intensive quantity, therefore it cannot be directly observed or measured—it can only be inferred. The lessons are designed to address students' tendency to focus on the most obvious variables and characteristics and to miss ones that are less obvious or non-obvious.

Section 1 Table of Contents

• Lesson 1: How Can Objects of the Same Volume Differ in Mass?
  • Understanding Goals
  • Background Information
  • Lesson Plan
    • Analyze Thinking
    • Review, Extend, Apply
• Lesson 2: What Are Some Models That Help Us Think About Density?
  • Understanding Goals
  • Background Information
  • Lesson Plan
    • Analyze Thinking
    • Review, Extend, Apply
• Resources for Section 1
  • Student Models Comparing Two Cylinders (PDF: 380 KB / 3 pages / 8½" X 11")
  • Dots-Per-Box sheet (PDF: 498 KB / 1 page / 8½" X 11")
• Endnotes for Section 1