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Get to Know Your Peeps

The chemistry behind these sticky marshmallow treats is seriously sweet!

By Jess McKenna-Ratjen

From the March/April 2025 Issue

Learning Objective: Students will explain how Peeps are made and plan an investigation that explores their properties.

Lexile: 830L; 600L

Key Focus Area: Matter,

Other Focus Areas: Engineering, Measurement & Data

Each spring, colorful chicks and bunnies appear in grocery stores. These aren’t real animals! They’re Peeps—soft, fluffy marshmallows coated in crunchy sugar.

Peeps have been popular seasonal treats for more than 70 years. They started out as plain yellow chicks. Now they come in many colors, flavors, and shapes!

What makes these candies so special? It has a lot to do with how Peeps are made!

Colorful chicks and bunnies appear each spring. You’ll see them in grocery stores. But they aren’t real animals! They’re Peeps. The candies are made of fluffy marshmallow. They’re coated in crunchy sugar.

Peeps are popular seasonal treats. They’ve been around for more than 70 years. They started out as plain yellow chicks. Now they come in many colors, flavors, and shapes!

What makes Peeps so special? It has a lot to do with how they’re made!

Sweet History

Peeps are a modern invention. But people have been chewing marshmallow treats for thousands of years. The earliest type of marshmallow was made from a plant called the marsh mallow. Its sweet sap has a gummy texture. That’s because it contains groups of tiny particles called polymers. Polymers give wood its sturdy structure and rubber its ability to snap back into shape after it’s stretched.

In ancient Egypt, people mixed honey and nuts with marsh mallow sap to create sweet, chewy cakes. In 17th-century France, doctors mixed the sap with egg whites and sugar to ease chest pain. You could get a prescription for marshmallows!

Today marshmallows aren’t medicine—and they’re not made of marsh mallow sap either. Modern candymakers found a different polymer that’s easier to use: a colorless, tasteless ingredient called gelatin. “Gelatin can stand up to almost anything,” says Douglas Mulford. He’s a chemist and a teacher at Emory University in Atlanta, Georgia. Gelatin is what gives Peeps their structure.

Peeps are a modern invention. But people have been eating marshmallow treats for thousands of years. The earliest type was made from a plant. It’s called the marsh mallow. Its sweet sap has a gummy texture. That’s because it contains groups of tiny particles. They’re called polymers. Polymers give wood its sturdy structure. And they give rubber its ability to stretch and snap back into shape.

People in ancient Egypt used marsh mallow sap. They mixed in honey and nuts. The result was a sweet, chewy cake. Doctors in 17th-century France used the sap too. They mixed it with egg whites and sugar. It was to ease chest pain. Marshmallows were medicine!

Today marshmallows aren’t made of marsh mallow sap. Modern candymakers found a different polymer. It’s easier to use. It’s colorless and tasteless. The ingredient is called gelatin. “Gelatin can stand up to almost anything,” says Douglas Mulford. He’s a chemist and teacher. He works at Emory University. It’s in Atlanta, Georgia. Gelatin is what gives Peeps their structure.

Making a Peep

The first marshmallow chicks were made by Rodda Candy Company in the 1940s. Each candy was formed by hand. Workers used a special bag with a narrow tip to pipe the shapes. It took 27 hours to finish one Peep!

In 1953, a company called Just Born took over making Peeps. One of the members of the Born family invented a machine that could shape the chicks automatically. It cut production time down to just 6 minutes! Since then, the process has stayed mostly the same (see How Peeps Are Made).

First, the cooks heat up water, sugar, and corn syrup. The sugar dissolves, or breaks apart, in the warm water. This forms a liquid mixture called a solution. The cooks add gelatin to the solution along with vanilla and other flavors.

Next, workers pump the liquid marshmallow through a machine that whips air into it. “Gelatin has very long particles that are twisted around each other and knotted together,” explains Mulford. “The gaps in between can trap air and hold their shape around it.”

Meanwhile, more sugar is mixed with food coloring in a giant metal barrel. The dyed sugar is spread onto a moving ramp called a conveyor belt.

Next, a device squeezes the whipped marshmallow into Peep form on top of the sugar-coated conveyor belt. A burst of air shoots out of a tube above, causing the sugar to fly up and stick to the Peeps’ gooey marshmallow surface.

Finally, a machine pops two eyes made of edible wax onto each Peep. Humans inspect the completed candies before they’re packaged. If they aren’t perfect, they’re melted down to start over again from the beginning.

Rodda Candy Company made the first marshmallow chicks. This was in the 1940s. Each candy was made by hand. Workers squeezed the shapes from a special bag with a narrow tip. It took 27 hours to finish one Peep!

A company called Just Born took over making Peeps in 1953. A Born family member invented a machine. It could shape the chicks on its own. It cut down the time to make Peeps to just 6 minutes! The process has stayed mostly the same ever since (see How Peeps Are Made).

First, the cooks heat up water, sugar, and corn syrup. The sugar dissolves. It breaks apart in the warm water. This forms a liquid mixture called a solution. The cooks add gelatin to the solution, plus vanilla and other flavors.

Next, workers pump the liquid marshmallow through a machine. It whips in air. “Gelatin has very long particles that are twisted around each other and knotted together,” explains Mulford. “The gaps in between can trap air and hold their shape around it.”

Meanwhile, sugar and food coloring mix in a giant metal barrel. The dyed sugar is spread onto a moving ramp. It’s called a conveyor belt.

Next, a device squeezes out whipped marshmallow. It’s formed into a Peep shape on top of the sugar-coated conveyor belt. A burst of air shoots out of a tube above. That causes the sugar to fly up. It sticks to the Peeps’ gooey surface.

Finally, a machine pops two eyes onto each Peep. The eyes are made of wax you can eat. Humans inspect the finished candies. Then the candies are packaged. Some aren’t perfect. They’re melted down to start over again.

How Peeps Are Made

With these steps, it takes only six minutes to make one batch of Peeps!

William Thomas Cain/Getty Images

1. Sugar, corn syrup, water, and gelatin are heated, mixed, and whipped.

Christopher Payne/Esto Photographics

2. Machines squeeze out marshmallow in Peep shapes.

Christopher Payne/Esto Photographics

3. The Peeps are blasted with sugar and given edible wax eyes.

William Thomas Cain/Getty Images

4. The treats are packaged and shipped to stores.

Which of these steps do you think takes the longest? Why?

How Peeps Are Made

With these steps, it takes only six minutes to make one batch of Peeps!

William Thomas Cain/Getty Images

1. Sugar, corn syrup, water, and gelatin are heated, mixed, and whipped.

Christopher Payne/Esto Photographics

2. Machines squeeze out marshmallow in Peep shapes.

Christopher Payne/Esto Photographics

3. The Peeps are blasted with sugar and given edible wax eyes.

William Thomas Cain/Getty Images

4. The treats are packaged and shipped to stores.

Which of these steps do you think takes the longest? Why?

Candy Creativity

About 2 billion Peeps are made each year. That’s enough to circle Earth two and a half times! There are many ways to eat them. Some people like to freeze them for a crunchy snack. Others roast them into s’mores—or even place them on a pizza!

The candies can also be used in fun science experiments. Mulford likes to show students what happens when a Peep is warmed up in a microwave. The heat causes the air caught in the gelatin to expand. The marshmallow expands with it. The treat puffs up to more than twice its size!

Mulford has also tried soaking Peeps in various liquids, like soda and vinegar. The strength of the gelatin allows the Peeps to keep their shape through most of his tests. But don’t worry! Gelatin dissolves easily in saliva. That makes the fresh candies completely safe to eat.

“People seem to either love or hate Peeps,” Mulford says. “For me, they’re just fun to play with!”

About 2 billion Peeps are made each year. That’s enough to circle Earth two-and-a-half times! There are many ways to eat them. Some freeze them for a crunchy snack. Others roast them into s’mores. People even put them on a pizza!

The candies can also be used in fun science experiments. Mulford likes to show students what happens to a Peep in a microwave. The heat causes the air inside the Peep to spread out. The treat puffs up to more than twice its size!

Mulford has also tried soaking Peeps in different liquids. They include soda and vinegar. The Peeps keep their shape through most of his tests. That’s thanks to the strength of gelatin. But don’t worry! Gelatin dissolves easily in saliva. So the candies are safe to eat. “People seem to either love or hate Peeps,” Mulford says. “For me, they’re just fun to play with!”

Peeps for All Seasons

Peeps aren’t just for spring! Check out some of the flavors and shapes for sale last year.

How do you think different Peeps flavors are created?

Peeps for All Seasons

Peeps aren’t just for spring! Check out some of the flavors and shapes for sale last year.

How do you think different Peeps flavors are created?

video (1)

Activities (11)

Quizzes (1)

Answer Key (1)

1. PREPARE TO READ (10 minutes)
Make observations and ask questions about Peeps.

Project a close-up photo of a Peep or pass around several Peeps inside clear zip-top bags. Invite students to share what they know about this treat. Then ask: What do you notice about your Peeps? What questions do you have about them? Have students discuss in small groups, encouraging them to build on one another’s observations and questions. (For example, “Someone noticed that Peeps have two little dots for their eyes. I also notice that the eyes bump out from the surface. I wonder how eyes are added to the Peeps.”) Reconvene and discuss as a class.

2. READ AND Analyze (20 minutes)
Read the article and describe how Peeps are made.

Read the article aloud, pausing after each section to briefly summarize it. Explain how piping works in baking and candy making and describe what piped means (or have students who have piped icing onto baked goods explain it). Compare the time it took to pipe each Peep individually to the time it takes to make a Peep at the factory.

Walk through the steps in the “How Peeps Are Made” sidebar. For each step, have students use their hands to show how they think the machine is moving (e.g., a stirring motion that gets faster to show whipping for step 1).

Have students reinforce their understanding with the Quick Quiz, referring to the article as they complete it.

3. RESPOND TO READING (30 minutes)
Design and conduct a hands-on investigation into the properties of Peeps.

Before distributing the Investigating Peeps hands-on activity, gather and prepare different materials that students could use for their Peeps investigation. These materials could include bowls of liquids like water, diet soda, or vinegar; heavy books; spoons; rulers; or waxed paper.

Play the “STEM in a Snap: Investigating Peeps” video, which explores what happens when a Peep is microwaved and encourages students to brainstorm questions to investigate. Then preview the Investigating Peeps hands-on activity. Discuss available materials and behavior expectations—emphasizing that these Peeps are not for eating. If needed, model how to write directions for an experiment by breaking down the steps of microwaving a Peep (e.g., put a Peep on a microwave-safe plate, open the microwave door, place the Peep in the microwave, and so on). Remind students that you’ll need to approve their investigation plan before they carry it out. Have students work in small groups. Reconvene and invite students to share their investigation and its results.

STEM INTEGRATION

MATH: Analyze a graph about candy preferences (CCSS Math: 3.MD.B.3, 6.SP.B.5)

Ask students what candies they like to eat in spring. Share the Circle Graph: Favorite Spring Candies activity. Have students complete the questions and then reconvene to discuss answers. To take it further, make a circle graph of the class’s top five favorite spring candies. Compare this graph with the graph in the activity.

ENGINEERING: Design a Peeps diorama (NGSS: ETS1.A, ETS1.B, ETS1.C)

Find a few appropriate examples of “Peeps dioramas” online to show the class. Ask: What materials were used? What was probably challenging about building these dioramas? Pair up students. Have them brainstorm, plan, and draw a design for their diorama. If desired, provide Peeps and other materials so students can create the diorama.