Conversation Piece

Source Institutions

Source Institutions

Add to list Go to activity
Activity link broken? See if it's at the internet archive
Focus sound through a balloon! In this Exploratorium activity, you'll use dry ice to create a balloon that's a sound lens.

Quick Guide

Preparation Time:
5 to 10 minutes

Learning Time:
5 to 10 minutes

Estimated Materials Cost:
$1 - $5 per student

Age Range:
Ages 6 - adult

Resource Type:


Materials List (per student)

  • Sturdy balloon, 12 to 16 inches (30 to 40 centimeters) in diameter
  • A way to fill the balloon with carbon dioxide (CO2) just before use, such as a tank of carbon dioxide or with dry ice.
  • Crushed dry ice (if no CO2 tank)
  • Thick, lined leather gloves (if no CO2 tank)
  • Tongs (if no CO2 tank)
  • A flask or 1- or 2-liter plastic soda bottle
  • Optional: Toy metal clicker or other noisemaker such as a radio or cell phone


  • Physical Sciences
    • Chemistry
    • States of Matter
      • Gases
    • Structure and Properties of Matter
      • Volume and Density
    • Vibration and Waves
      • Sound


This resource is part of:

Access Rights:

  • Free access