Friday Do-Over: Blowing up a Balloon with Yeast or Baking Soda and Vinegar

Stuck inside? Try this easy science project or visit my Indoor Activities for Kids page. First Published 3/2/09.

Did you know you can blow up a balloon with common household ingredients? We chose two different methods to make the necessary carbon dioxide: yeast, and baking soda and vinegar (an old standby favorite).

First the supplies. (hint: set up on towel)It takes time for the yeast to produce enough gas to inflate the balloon, so start that one first.
Put a spoonful or two of sugar in a bottle.Fill with water about 3/4 full.Add a spoonful or two of yeast. Here's something I've always wondered: if yeast is a living organism, how come it still works after you freeze it? Some food for thought.Shake. Shake. Shake.Place balloon over bottle opening.At the risk of losing my G-rating, here is what it looked like after about 30 minutes.Next, the soda and vinegar balloon.
First, use the funnel to fill balloon with baking soda. If your funnel is pathetic you have to use a toothpick to encourage soda to go through opening.Then, pour some vinegar in the bottle.Add water. This raises the liquid level so you don't overuse the vinegar and the gas fills the balloon rather than just the bottle.Place balloon over bottle opening and then shake soda from balloon into the bottle.Bigger...Bigger...Biggest!Of course experiment must be repeated.This is a very satisfying activity for a 4 year old who loves action and reaction. It also provides further free play with the materials, producing much bubbling, oozing and fizzing, along with one very wet towel.

Science Books we like:
The Book of Totally Irresponsible Science: 64 Daring Experiments for Young Scientists
Science in Seconds for Kids: Over 100 Experiments You Can Do in Ten Minutes or Less
Science is Simple: Over 250 Activities for Preschoolers
Science Play (Science for 2-6 year olds)