Making Bread with Yeast!

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SWBAT explain how decomposers impact our everyday lives, beyond being a part of natural ecosystems.

Big Idea

In this lesson, students will research and investigate yeast. As a class, we will make bread and students will observe how the decomposition process aids the bread-rising process.

Lesson Overview

Inquiry Based Instructional Model

To intertwine scientific knowledge and practices and to empower students to learn through exploration, it is essential for scientific inquiry to be embedded in science education. While there are many types of inquiry-based models, one model that I've grown to appreciate and use is called the FERA Learning Cycle, developed by the National Science Resources Center (NSRC):

1. Focus

2. Explore

3. Reflect

4. Apply

A framework for implementation can be found here

I absolutely love how the Center for Inquiry Science at the Institute for Systems Biology explains that this is "not a locked-step method" but "rather a cyclical process," meaning that some lessons may start off at the focus phase while others may begin at the explore phase. 

Finally, an amazing article found at, How Inquiry-Based Learning Works with STEMvery clearly outlines how inquiry based learning "paves the way for effective learning in science" and supports College and Career Readiness, particularly in the area of STEM career choices. 

Unit Explanation

In this unit, students will first develop an understanding of the biotic and abiotic factors within ecosystems, the characteristics and classification of living organisms, and how plants and animals obtain and use energy to fulfill their needs. 

Then, students will delve deeper into the NGSS standards by examining the interdependent relationships within an ecosystem by studying movement of matter between producers, consumers, and decomposers by creating models of food chains and food webs.  

At the end of this unit, students will study ways that individual communities can use science ideas to protect the Earth's resources and environment.  

Summary of Lesson

Today, I will open the lesson by showing the students how to activate yeast and make bread! Students will then explore yeast further by researching an online resource on yeast. At the end of the lesson, students will reflect and apply their new understanding of yeast by sharing their research and observing the rising bread.

Next Generation Science Standards  

This lesson will support the following NGSS Standard(s):

5-LS2-1.    Develop a model to describe the movement of matter among plants, animals, decomposers, and the environment.  

Scientific & Engineering Practices

For this lesson, students are engaged in the following Science & Engineering Practice:

Science & Engineering Practice 2: Developing and Using Models

Today, the bread-making process will model the role of decomposers in ecosystems. Students will witness how yeast produces carbon dioxide as it decomposes sugar. 

Crosscutting Concepts

To relate ideas across disciplinary content, during this lesson I focus on the following Crosscutting Concept

Crosscutting Concept 2: Cause and Effect

The class will test the cause and effect relationships when yeast is added to water temperature is cold, just right, and hot. Students will also analyze the cause and effect relationships when activated yeast is added to bread dough.

Disciplinary Core Ideas

In addition, this lesson also aligns with the following Disciplinary Core Ideas

LS2.A:  Interdependent Relationships in Ecosystems

The food of almost any kind of animal can be §traced back to plants. Organisms are related in food webs in which some animals eat plants for food and other animals eat the animals that eat plants. Some organisms, such as fungi and bacteria, break down dead organisms (both plants or plants parts and animals) and therefore operate as “decomposers.” Decomposition eventually restores (recycles) some materials back to the soil. Organisms can survive only in environments in which their particular needs are met. A healthy ecosystem is one in which multiple species of different types are each able to meet their needs in a relatively stable web of life. Newly introduced species can damage the balance of an ecosystem. (5-LS2-1)

LS2.B:  Cycles of Matter and Energy Transfer in Ecosystems

Matter cycles between the air and soil and among plants, animals, and microbes as these organisms live and die. Organisms obtain gases, and water, from the environment, and release waste matter (gas, liquid, or solid) back into the environment. (5-LS2-1)

ELA Integration

To add depth to student understanding, when I can, I'll often integrate ELA standards with science lessons. Today, students will work on meeting CCSS.ELA-LITERACY.RI.5.2: Determine two or more main ideas of a text and explain how they are supported by key details; summarize the text. In this lesson, students will be locating key details that support a main idea.

Choosing Science Teams

With science, it is often difficult to find a balance between providing students with as many hands-on experiences as possible, having plenty of science materials, and offering students a collaborative setting to solve problems. Any time groups have four or more students, the opportunities for individual students to speak and take part in the exploration process decreases. With groups of two, I often struggle to find enough science materials to go around. So this year, I chose to place students in teams of three! Picking science teams is always easy as I already have students placed in desk groups based upon behavior, abilities, and communication skills. Each desk group has about six kids, so I simply divide this larger group in half. 

Gathering Supplies & Assigning Roles

To encourage a smooth running classroom, I ask students to decide who is a 1, 2, or 3 in their groups of three students (without talking). In no time, each student has a number in the air. I'll then ask the "threes" to get certain supplies, "ones" to grab their computers, and "twos" to hand out papers (or whatever is needed for the lesson). This management strategy has proven to be effective when cleaning up and returning supplies as well!  


30 minutes

Lesson Introduction & Goal 

I introduce our learning goal: I can explain how decomposers impact our everyday lives, beyond being a part of natural ecosystems. 

I refer to the Decomposer Poster from yesterday and ask the following review questions: 

1. What is a decomposer? (a living organism that decomposes dead organisms)

2. Why are decomposers important to ecosystems? (they return needed nutrients back to the soil for plants to use)

3. What are some types of decomposers? (bacteria, fungi - like mushrooms, mold, & yeast)

Activating Yeast

Today, students will be completing further researching on yeast, but first I want to break away from the traditional science lesson and provide my students with a real-world and memorable experience with using yeast to make bread! I think that it's important to take advantage of every opportunity to connect science to real world applications! Decomposers are not just part of a natural pond ecosystem, they impact our everyday lives as well. 

It's important to start the lesson by activating the yeast right away as the yeast needs to set 5-10 minutes, or until the "yeast begins to foam vigorously!" 

I invite students to the back table to watch as I show them how to activate (or hydrate) bakers yeast. I purposefully heat the water too much so that students can see how a baker might add cold water to the hot water in order to obtain the right temperature. Also, this supports the fact that all organisms (plant, animal, fungus, etc.) can "survive only in environments in which their particular needs are met." (LS2.A: Interdependent Relationships in Ecosystems)

Finally, we achieve the correct temperature and we're able to add the yeast. Student reactions are priceless! Some love the smell while others think it's the worse smell ever: Yeast Video. Either way, I know they won't ever forget this day!  


I want to inspire even more interest in yeast and capitalize on student curiosity, so I show a video of a fun investigation with a yeast while we wait for our yeast to foam up! 

Yeast Temperature Investigation

As students watch the above video (two times, upon student request), I set up a little investigation for students to observe the effect of water temperature on yeast. I grab 3 Beakers & 3 Thermometers and add water at different temperatures in each beaker (76 degrees, 114 degrees, and 156 degrees). After the video, I explain the investigation to students and they predict which environment yeast will thrive in the best. Most students agree that the 114 degree water will be the best for yeast. Here's what the beakers will look like at the end of today's lesson: Yeast Investigation with Water Temperature. I wish I would have used colder water than 76 degrees to create a more dramatic difference! 

Making Bread

Prior to this lesson, I set up a Bread-Making Station at the back of the room to expedite the bread-making process! I invite students to join me at the back table at this time. To include students, I randomly pull name sticks from a jar and ask one to add the sugar, one to add the salt, then flour, and I asked another to stir the ingredients. 

At this point, our yeast looks amazing (Yeast Foaming Up) and we're ready to start making bread! I demonstrate how bakers add yeast, water, and butter to dry ingredients to create a runny dough mixture: Making Bread. Next, I ask student volunteers to add one cup of flour at a time while I knead the bread. If we had more time, I would have split the dough into parts and asked students to take part in the kneading process! 

After the bread is ready, a student butters the bowl and we place the dough back in the bowl. Another student covers it with plastic wrap. Then, we place the bowl inside a tub of warm water: Bread Dough Before. I can't wait for the students to witness the bread rising! 


30 minutes

Getting Ready

While the bread is rising, I want students to complete their own research on yeast! So, I pass out the following graphic organizerand ask students to write "What is Yeast?" in the middle circle. I also share this link with students for researching yeast on their computers. 

Monitoring Student Understanding

Once students begin working, I conference with every group. My goal is to support students by asking guiding questions (listed below). I also want to encourage students to engage in Science & Engineering Practice 7: Engaging in Argument from Evidence

  1. Why do you suppose ____? 
  2. What have you found so far? 
  3. Has your thinking changed? 
  4. What evidence do you have? 
  5. How did you decide _____?
  6. What conclusion can you draw about ____?


Student Work


Often times students record research notes in their journals, however, they seem to love having a graphic organizer today for organizing their notes. For students who struggle with reading and researching, the graphic organizer provides a clear goal (fill 4 sections) and gives them an end in sight! Other students are careful to only pick the most important facts as there were only four sections (which encourages students to think). Some students choose to divide the four sections into eight sections so they can collect more facts on yeast! 

Reflect & Apply

10 minutes

Sharing Findings

Now that students have built meaning and understanding by exploring yeast further, it is important to provide students with the opportunity to share their findings. For this reason, I invite students to answer the question, "What is yeast?" 

Students raise their hands to share: 

  • Yeast are single celled fungi.
  • Yeast cells are egg-shaped and can only be seen with a microscope.
  • Yeast cells digs food to obtain energy for growth.
  • It takes 20,000,000,000 yeast cells to weigh one gram.


After students share their findings, we talk about yeast further: So you already know that yeast is a microscopic organism that acts as a decomposer. It can be found all around us, in the soil, on plants, and even in the air. Can anyone remind me of what happened yesterday, when we placed yeast, water, and sugar inside a bottle and covered it the mouth with a ballon (Yeast & Balloon Demonstration)? (Students: The balloon began to fill with carbon dioxide.)

You're right! As the yeast began decomposing the sugars, they produced carbon dioxide in the process. (This concept supports LS2.B: Cycles of Matter & Energy Transfer in Ecosystems: Organisms obtain gases, and water, from the environment, and release waste matter (gas, liquid, or solid) back into the environment.)

A similar process is happening in our bread today. Carbon dioxide from the yeast has filled thousands of tiny balloon-like bubbles in the dough. This has made our bread rise and it will also give the bread an airy texture after it's baked. 

At this point, I walk around the classroom with the bowl of bread so that students can see how much it has risen: Bread Dough After. Students immediately want to know if I'm going to bake it and if they get to have bread tomorrow. After I tell them YES, excitement fills the air! One students even asks if he can bring in jelly! 

Teacher Note: The bigger picture that students walked away with today is the fact that tiny microorganisms (such as yeast, bacteria, and fungi) are all around us, decomposing organic matter and producing carbon dioxide. Today's lesson provided students with the opportunity to expereince the work of microscopic organisms, even if they can't see the individual yeast cells themselves!