Did you know that humans aren’t the only ones who like sugar? In this Valentine’s Day science experiment, we’ll discover what happens when you give sugar to yeast.
This science experiment is part of our latest unit study, Valentine’s Day School! In Valentine’s Day School, you’ll learn about topics like symbolism, love languages, how Valentine’s Day is celebrated around the world, and all about Esther A. Howland, the Mother of the American Valentine. You’ll also dive into fun, hands-on projects that cover a wide range of subjects—like this sugar and yeast science experiment!
Want to take a peek inside? Grab these FREE Printable Valentine’s Day Cards that also includes a sample from Valentine’s Day School! The cards will be emailed to you instantly, and you’ll be brought to the How Wee Learn shop so you can take a closer look at Valentine’s Day School. Get yours here:
Valentine’s Day Science Experiment… with SUGAR!
To complete this Valentine’s Day science experiment, you will need:
- Two (or more) yeast packets
- Warm water
- Two bottles (empty water or pop bottles work well)
- Two (or more) balloons
- Funnel (optional)
- Pencil and paper to record observations
- Permanent marker (optional)
- Masking tape(optional)
Valentine’s Day Science Experiment Instructions
To start, stretch out the balloons by blowing them up and letting them deflate again a few times.
When you have a balloon blown up, you could draw a heart, a smiley face, or a sweet little message on the balloon with a permanent marker (don’t knot the balloon, just pinch the mouth of the balloon closed while you draw or write on it).
Set the balloons aside.
This is also a wonderful time to practice sounding out and spelling words as you label your experiment. Like shuger …er, sugar.
Grab your two empty bottles and pour one packet of yeast in each bottle. Next, fill each bottle about 2/3 of the way full with warm water. Give them a little swirl to dissolve the yeast.
In one of the bottles, we’re going to leave the mixture as is. In the other bottle, we’re going to add sugar. We’ll attach a balloon to the top of each bottle and see what happens.
Time for a prediction!
What do you think will happen? Make your prediction!
Now stretch a balloon over the top of the first bottle and set it aside.
In the second bottle, add 2 tbsp of sugar. Gently swirl the bottle to mix in the sugar, then stretch a balloon over the top of the bottle. It won’t be long before you start to see some changes happening!
Make sure there is a good seal between the balloon and the bottle. We noticed part-way through our experiment that the balloon didn’t fully cover all of the ridges in one spot, and we could—SPOILER ALERT!—see some bubbles seeping through.
Time for some observations!
Do you notice anything happening right away? Record your observations on a piece of paper.
Older children can draw a picture of the two bottles, label them, and write a sentence about what they observe. Younger children or pre-writers can simply draw a picture of what they observe.
Your child may also observe, as they drag their finger through the spilled sugar and put it in their mouth, that sugar tastes… “sweet.” Why yes, yes, it does.
Check back on the two bottles and balloons every 10 minutes for an hour, noting the changes that you observe. We noticed the biggest changes around 5 minutes, 10 minutes, and 20 minutes.
What’s different between the two bottles and balloons? Why do you think this might be?
So, what’s happening in this sugar and yeast science experiment?
Humans aren’t the only ones who like to eat sugar—yeast does too!
Yeast is a single-celled microorganism. When yeast is cold and dry, the microorganisms are not active. When the yeast dissolves in the warm water, however, it becomes active.
But, just like humans, yeast needs food! You’ll notice that the bottle with yeast and warm water does not affect the balloon. When we give the yeast sugar, however, the yeast eats the sugar and releases carbon dioxide in a process called fermentation. The carbon dioxide fills the bottle and the balloon.
This is also a wonderful time to chat about the difference between solids, liquids, and gases. Is carbon dioxide a solid, liquid, or gas? How do you know?
Now, fair warning, the response I received after explaining what I thought was a really cool experiment was:
“So you’re telling me that people gather up little living microorganisms, package them, and sell them to people!? That’s gross!”
I proceeded to get out the bread, point out the nice, airy, fluffy inside, and explain, “Yes! But it’s not gross; yeast is what gives us yummy, fluffy bread! Bakers use yeast when making bread. As the yeast feeds on sugars during the baking process, it releases carbon dioxide. This makes bubbles in the bread, which makes it nice and fluffy.”
Aaaaand now I have a child who no longer wants to eat bread.
So… whether or not you want to risk your child’s love of bread is up to you, but the experiment was still totally worth it and really cool to watch!
In fact, when we were satisfied that the balloon in the first sugar concoction wasn’t going to grow anymore, we dumped the rest of the sugar in the first bottle so we could watch it inflate again.
Change it up! Sugar & Yeast Science Experiment Extensions
Try this experiment again, but this time, vary a different element to see what happens. You could try changing:
- Water Temperature. Which works best? Cold water, warm water, or hot water?
- Type of Sugar. Try adding honey, brown sugar vs. white sugar, corn syrup, or even sprinkles! Which do you predict will make the most carbon dioxide?
- Type of Yeast. We used Quick Rise Instant Yeast for this experiment, but you could compare the difference between Quick Rise Instant Yeast and Traditional Active Dry Yeast.
- Bottle or Balloon Size. What happens if you use a big 2L pop bottle instead of a water bottle? What happens if you use small water balloons instead of regular-sized ones?
Encourage those curious minds to come up with their own combination of variables! Which one results in the biggest balloon?
I hope you enjoyed this Valentine’s Day science experiment! If you want even more fun, hands-on activities to learn and make memories together this season of love, I invite you to check out Valentine’s Day School.
Get in the lovey-dovey spirit and join us!
Thank you so much for reading, sweet friend!