What’s in Your Breath?

We breathe in and out all the time. What’s in the air we breathe out from our lungs (exhale), and how is it different than the air we breathe in (inhale)? In this activity, learners test to see if carbon dioxide is present in the air we breathe in and out by using a detector made from red cabbage. Learners experiment by exposing the detector to air from a balloon filled by breath, a pump, or a carbon dioxide-producing mixture of baking soda and vinegar. Step-by-step instructions are included with photos. Activity guide includes a “What’s going on?” explanation and connections to relevant science concept such as the composition of air we breathe, how alveoli in our lungs absorb oxygen and release carbon dioxide, and the negative effects of smoking and air pollution on our lungs.

Materials List:

• Leaf of red cabbage


• 1 L of water


• Blender


• Liquid measuring cup or large container


• Strainer


• 4 large, clear drinking glasses or containers


• Marker


• Masking tape


• 4 drinking straws


• 3 large balloons (about 20-30 cm when in inflated)


• Ruler


• Funnel


• 25 ml (5 teaspoons) of baking soda


• 60 ml (1/4 cup) of white vinegar


• Empty soda or water bottle, approximately 500 mL


• Bicycle tire or balloon pump


• Newspaper and/or paper towels


• Rubber band (optional)