Bread, Yeast, & Science

Amanda Bennett

The science of yeast has astounded kids for generations, and now is the time to show them how it works!

old weather is here, and the time is ripe for some indoor science. This season is a great one for baking experiments that the whole family can enjoy. Bread, yeast and kids always bring out fun as well as plenty of fascination. Don’t be surprised to hear comments along the lines of “You mean that yeast creates gas, too?”

The science of yeast has astounded kids for generations, and now is the time to show them how it works in bread, along with a bit of baking and tasting, of course. Ask your children a few questions to find out what they already know:

What can they tell you about bread? What are their favorite kinds of bread? What makes some kinds of bread light and fluffy?

Bread goes way back in the history of civilization and has played a key role in the daily lives of people around the globe. Did you know that bread is mentioned 255 times in the NIV version of the Bible? One of the earliest memories of the idea of yeast for many children is in the story of the Israelites preparing to flee Egypt, after the first Passover:

“So the people took their dough before the yeast was added, and carried it on their shoulders in kneading troughs wrapped in clothing.”

—Exodus 12:34

“With the dough the Israelites had brought from Egypt, they baked loaves of unleavened bread. The dough was without yeast because they had been driven out of Egypt and did not have time to prepare food for themselves.”

—Exodus 12:39

The next questions are usually “What difference does yeast make?” and “What is yeast?”

Yeast: tiny, single cells of certain fungi that are used to make bread, alcohol, and some medicines.

—Wordsmyth Online Dictionary

Now we are moving into the fun part—the science of yeast. If yeast is a fungus, what exactly is a fungus? Is it a plant or an animal?

Fungi are neither plants nor animals—they have a classification all their own. Like mushrooms and mildew, yeast is a type of fungus.

Baking yeast is made up of dormant fungi that just need food, water and warmth to spring back to life.

Why do we put fungi into bread dough? Well, because it helps the dough to rise. Have each child take a piece of bread and look closely at that piece. What do they see?

Bottle and Balloon Experiment list and directions

They should notice the tiny holes in the slice of bread—holes formed when the yeast ferments, giving off carbon dioxide and alcohol. The carbon dioxide is trapped in the bread dough and forms bubbles during the baking process. The alcohol evaporates during baking, and the yeast is killed from the high temperature in the oven.

In other words, yeast causes dough to rise by producing gas, which forms tiny pockets all through the bread dough. The idea of gas-producing yeast fascinates most children, and that opens the door to this fun and very simple experiment.

Now is a good time to make a loaf of bread so that they can watch science at work. There are many simple bread recipes available online, and one of my favorites is the French bread recipe at RedStarYeast.com. Find one that matches your ingredients on hand, and let the children help you as you move through the steps to make the bread. They love the “punching down the dough” part of the process, almost as much as the eating of the fresh bread.

When making bread, you’ve got the perfect opportunity to work on memorizing the Lord’s Prayer with them. See if they notice the mention of bread in the prayer on their own, and point it out if they don’t catch it. We depend on God for everything, even the food that we eat.

I hope that you and your family have fun with these experiments and getting to enjoy the fruits of your labor.

manda Bennett is a wife, mom, writer, engineer, and new grandmother. She has written over 100 unit studies, many articles, as well as blog posts. She homeschooled their three children through high school and learned much more through the process. Her three children are now off chasing their dreams (homeschooling mission accomplished) as an ER veterinarian, a tree farmer, and a software developer. Amanda has been busy with travel and photography and is once again writing. She lives in the Appalachian Mountains with her husband, and they are loving this new phase of life called grandparenting.

Back to Issue