Last week at our Mad Scientist Club we learned about combining two substances to make a gas. We combined baking soda and vinegar and yeast, sugar and water to create carbon dioxide. When the gas forms, it expands. We discovered that by placing the substances in an enclosed container (plastic bottle with balloon on top, or a zip lock bag) that the expanding gasses will fill up the container. WIth the balloon, it inflated the balloon. With the zip lock bag, it explodes when dropped!