Sink or Swim?

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In this activity, learners identify different plastics in a mystery bag. Learners discover that plastics are classified #1 through #7. Learners then categorize plastics based on characteristics such as density, transparency, and rigidness.

Quick Guide

Preparation Time:
10 to 30 minutes

Learning Time:
45 to 60 minutes

Estimated Materials Cost:
$1 - $5 per group of students

Age Range:
Ages 8 - 14

Resource Types:
Activity, Lesson/Lesson Plan


Materials List (per group of students)

  • #1 plastic (clear bottle, e.g., soda, water, mouthwash, or salad dressing bottle)
  • #2 plastic (opaque bottle, e.g., milk, orange juice, shampoo, or lotion bottle)
  • #4 plastic (lightweight bag, e.g., bread, sandwich, and some grocery bags)
  • #5 plastic (tub, e.g., yogurt, cottage cheese, or margarine container)
  • #6 plastic (e.g., Styrofoam products, disposable plates and cups, plastic utensils)
  • scissors
  • sandwich or paper lunch bags
  • plastic containers learners bring from home
  • small, clear container
  • water
  • paper and pencils


  • Earth and Space Science
    • Earth's History
  • Life Sciences
    • Ecology
  • Engineering and Technology
    • Engineering
      • Environmental Engineering
      • Metallurgy and Materials Engineering
  • Mathematics
    • Data Analysis and Probability
      • Data Analysis
      • Data Collection
  • Physical Sciences
    • Structure and Properties of Matter
      • Atomic Structure
      • Mass and Weight
      • Volume and Density
  • The Nature of Science
    • Science and Society
      • Risks and Benefits
    • The Scientific Process
  • The Nature of Technology
    • Technology and Society
      • Impacts of Technology
      • Technology and the Environment

Informal Categories

  • Nature and Environment


To use this activity, learners need to:

  • see
  • touch

Learning styles supported:

  • Involves teamwork and communication skills
  • Uses STEM to solve real-world problems
  • Involves hands-on or lab activities

Culture, ethnicity, and gender

  • Girls

    • Explicity developed for this group
    • Acknowledges this group's contributions to STEM
    • Highlights STEM opportunities for this group
    • Identifies role models or mentors in STEM fields from this group
    • Uses inclusive images of people from this group


Components that are part of this resource:

Includes alignment to state and/or national standards:

This resource is part of:

Access Rights:

  • Free access



  • All rights reserved, Twin Cities Public Television, Inc., 2010

Funding Sources:

  • National Science Foundation, 0813519
  • ExxonMobil