Yeast and Sugar Science Fair Project

Yeast and sugar science fair project

In this Yeast and Sugar Science Fair Project, we’ll watch yeast feed on sugar to fill a balloon with air. A fun science project for kids that’s with household, everyday materials.

Our Inspiration

I’ve been baking bread just about every day for the past three weeks (nothing too crazy since it’s all done in the bread maker), but last week my 3.5 year old and I got into a discussion about the properties of yeast.

We like to tinker and  experiment — big surprise, I know — and decided to see what would happen if we mixed yeast with warm water.

My preschooler took this job very seriously, poured the water into a bowl, added a couple teaspoons of yeast, and waited a few patient minutes before she said, “it makes a brownish color.” True, and to make it bubble like it does in bread, we needed to activate it with sugar.

What’s so great about an experiment like this is that it’s easy to do with household materials, and it’s ripe for authentic child-generated questions and observations. When I asked what she thought would happen if we added sugar to the yeast she said, “I don’t know! Let’s mix them and find out!.”

In this Yeast Sugar Experiment, we'll watch yeast feed on sugar to fill a balloon with air. A fun science project for kids that's with household, everyday materials.

Supplies: Yeast and Sugar Science Fair Project

  • Sugar, 2 tablespoons
  • Active Dry Yeast, 1 packet or 2 1/4 tablespoons
  • Balloon
  • Warm water (105-115 degrees F, 40.5-46 degrees C)
  • Mixing bowl + funnel
  • Bottle that you can fit a balloon over

Science Projects for Kids | Yeast and Sugar Experiment

Mix the yeast and sugar into the warm water and stir. I noticed that N was sniffing the concoction and asked her what it smelled like. She said “poop.” I could see what she was saying. Consider yourself warned.

Once it all dissolves, pour the mixture into the bottle and cover the bottle with the balloon.

Science Projects for Kids | Yeast and Sugar Experiment

After a few minutes you’ll be amazed by something like this!

Science Projects for Kids | Yeast and Sugar Expriement

Will it blow off the bottle?

N wanted to feel it as it filled with air. She noticed the balloon was getting bigger and wanted to know how big it would get, wondering out loud, “will it fill up all the way and blow off the bottle?”

Good question!

Science Projects for Kids | Yeast and Sugar Experiment

My handy-dandy ship captain sister (no joke — that’s her job!) was visiting, and put herself right to work as chief measurer.

Science Projects for Kids | Yeast and Sugar Experiment

Move it to a safe spot

Once the bottle filled up completely, we moved the whole yeast sugar experriment to the sink. The bubbles were slow-moving, and there was nothing to worry ourselves with, but N enjoyed pulling the balloon off and watching the foam slowly pour over the bottle’s top.

Science Projects for Kids | Yeast and Sugar Experiment

Ideas for Extending this Experiment

As we went through the process, I thought of a few fun extensions for older kids or those who want to take this further. You could play around with food coloring/liquid watercolors, have a few bottles going at once and compare the results of different sugar:yeast ratios, or compare the results of different water temperatures.

I found my recipe at The Exploratorium’s Science of Cooking series, where we also learned that as the yeast eats the sugar it makes carbon dioxide, which is essentially the same process that yeast goes through in our bread dough.

Mmmmm. I’m off to eat some whole wheat cranberry walnut oat bread. Toasted. With butter and Maldon salt. How do you like your bread? And have you played around with yeast concoctions?

More Science Experiments for Kids

If you enjoyed this project, you’ll love this article: Science Fair Project Ideas.

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In case you blinked and missed it, TinkerLab rounds up all the great stuff on the internets on keeping you and your critters creative and wraps it up for you in a tidy newsletter! (And throws in some secret giveaways for good measure!)  – Yuliya P., San Francisco, CA

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How to Make Rock Candy on a Stick

This fun science project for kids is easy to set up with sugar, skewers, and a few kitchen tools.

How to make rock candy on a stick

How to make Rock Candy on a Stick

We’ve been making rock candy, and in the true spirit of experimentation we made three batches (and hope that we finally got it right!). There are so many ways to get this confection started, and I’ll share a few thoughts and links for those of you who might want to give it a try. The thing about rock candy that appealed to me is that the ingredients are simple, and I already had them all on hand (Yipee!).

Rock Candy: Ingredient List

adapted from Rock Candy Recipes via The Exploratorium and Science Bob

  • 2+ cups sugar
  • 1 cup white sugar
  • sauce pot
  • wooden spoon
  • clean, narrow jar/s or glass/es
  • wooden skewers
  • clothes pins
  • candy thermometer or digital thermometer that reaches 240 degrees F
  • wax paper
  • food coloring (optional)
  • vanilla extract or other flavoring (optional)

At least 3 hours ahead of time:

Snip the ends off your skewers so they’re not sharp. Dip the ends of the skewers into a simple syrup mixture (sugar + water, 2 sugar: 1 water, cooked until the sugar dissolves) and then roll the skewers in sugar. Set aside on wax paper until dry. This might not take long at all, but we gave it three hours. If you don’t have skewers, you could use the string method (see photo below). The skewer or string act as a “seed” that attracts the cooling sugar to adhere to it.

(String method: Dip your cotton string in the sugar solution, roll it in sugar, and allow it to completely dry. This could take 24+ hours.)

Steps: Rock Candy with Kids

I don’t normally allow my daughter to cook boiling hot things at the stove (do you?), but she begged me to get involved and she did a great job! What are your thoughts on this? Any tips for kitchen safety that also allow for kids to fully participate?

  • Boil 1 cup water in a small saucepan
  • Slowly add 2 cups of sugar and mix with a wooden spoon until sugar dissolves
  • Cook sugar solution until it’s 240 degrees F (also known as the soft ball stage in candy making). Some rocky candy recipes say to simply boil the solution until the sugar dissolves. I tried this and it didn’t work for me, but let me know if it works for you!
  • Remove from the heat

  • Add food coloring. Be generous.
  • Add flavor (we made one batch with pure vanilla extract and another with real lemon extract). We added about 1 tbsp. lemon, and 1/2 tsp vanilla.

  • Dangle sugar-covered skewer into sugar solution so that it’s about 2/3 of the way down the jar.
  • Attach a clothespin to the top to keep it in place. We put 2-3 skewers in the jars. I wonder if this will be too crowded to work?

And now we wait. Somewhere between 3 and 7 days!! Already feeling impatient, but I’m sure it’ll be worth it! Sugar will form on the surface, and I’ve read that you can scoop it out and enjoy it while waiting for the rock candy to form.

Well, the truth is that we couldn’t really wait 🙂 Before washing the pot, we coated a few spoons with the hot candy. And as soon as they cooled, we were treated to homemade vanilla and lemon lollipops!

More Science Projects for Kids

If you enjoyed this project, you’ll love this article: Science Fair Project Ideas.

Is this your first time here?

Join the Tinkerlab network and be the first to know about simple art + science projects for kids, creativity tips, and simple ideas that will make your life more creative. Sign up for our newsletter.

TinkerLab Newsletter

In case you blinked and missed it, TinkerLab rounds up all the great stuff on the internets on keeping you and your critters creative and wraps it up for you in a tidy newsletter! (And throws in some secret giveaways for good measure!)  – Yuliya P., San Francisco, CA

Join our community and you’ll learn:

  • How to simplify your life and make more room for creativity
  • How to make hands-on making a part of your everyday life
  • Easy, actionable ways to raise creative kids

+++++

Resources

Candy Stages, from The Exploratorium

Rock Candy Crystal Kit, from Steve Spangler. In case you don’t want to mess around with the messiness of this project.