Authentic Lessons for 21st Century Learning

Lesson 5E Lesson

Microbes and Manure = Biofuel

Anaerobic Respiration

Danny Mattox | Published: December 17th, 2025 by K20 Center

  • Grade Level Grade Level 9th, 10th, 11th, 12th
  • Subject Subject
  • Course Course Environmental Science
  • Time Frame Time Frame 3-20 class period(s)
  • Duration More 200 minutes

Summary

In this lesson, students explore gas production by micro-organisms by designing and experimenting with biogas digesters made from small water bottles.

Essential Question(s)

Can waste be converted and used for energy?

Snapshot

Engage

Students observe a demo of a mini biogas digester, a "burping bottle."

Explore

Students design and conduct their own experiments to test variables in biogas production.

Explain

Students watch videos, read about the science of biogas, and continue collecting experimental data.

Extend

Students continue to collect data from their experiments and read multiple articles about converting manure to energy. Students also submit proposals for their final presentations.

Evaluate

Students conduct a Gallery Walk to share the results of their in-class experiments and prepare a presentation advocating the use of biogas digestion in their community.

Materials

  • Small water bottles

  • Scales/balances

  • Manure (cow or horse is easiest to find)

  • Funnels

  • Gloves

  • Goggles

  • Water

  • Lighter or matches

  • Beaker

  • Paper

  • Food waste

  • Wood chips

  • Apple cider

  • Plastic

  • Oatmeal

  • Other sources of organic and inorganic materials the students can use when designing and testing their biogas digesters

  • Balloons that will fit over the mouth of a water bottle

  • Student devices with internet access

  • Computer presentation software (Google Slides, Microsoft Word, etc.)

  • Markers, crayons, and colored pencils

  • Over-sized sticky notes, butcher paper, or bulletin board paper

OPTION 2: For SME Review:

  • For Biogas Digester Experiments:

    • Small water bottles

    • Scales/balances

    • Manure (cow or horse recommended)

    • Funnels

    • Gloves and goggles

    • Water

    • Shredded newspaper (preferred carbon source)

    • Balloons that fit over water bottle mouths

    • Optional inputs: food waste, wood chips, oatmeal, apple cider, plastic, or other materials for testing

  • For Demonstrations (teacher use only):

    • Lighter or long matches

    • Beaker

  • For Presentations:

    • Student devices with internet access

    • Computer presentation software (Google Slides, PowerPoint, etc.)

    • Oversized sticky notes, butcher paper, or bulletin board paper

    • Markers, crayons, or colored pencils

Lab Preparation

Prepare the demo biogas digester 4–5 days before class. It's best to have several bottles for each class, so every student can experience the demonstration.

  1. In a small container, mix manure and water until the mixture has a smoothie-like consistency. There is no exact ratio, just add enough water to achieve the correct texture.

  2. Use a funnel to pour the mixture into an empty water bottle.

  3. Add shredded or cut-up paper to the bottle. Newspaper works best because it breaks down more easily than notebook or copy paper. The paper serves as a carbon food source for the microorganisms in the manure.

  4. Seal the bottle and allow it to sit undisturbed for 4–5 days before beginning the Engage portion of the lesson.

Tip: Wear gloves when preparing the bottles, and store them in a place that is easy to clean in case of leaks or spills.

Engage

Begin this lesson only after the bottles have sat for 4–5 days.

Use the attached Lesson Slides to introduce the lesson and review the essential question and learning objectives on slides 3 and 4.

Move to slide 5, show students a prepared bottle. Ask them to take out a piece of paper and record their observations as you “burp” the bottle. Hold the bottle out in front of you and gently unscrew the cap. This will release a small amount of methane, producing a sound similar to opening a soda bottle—but with a much different odor. Go around the room "burping" bottles for class.

After you're done burping the bottle and igniting the gas, ask students to turn to their Elbow Partner and discuss these questions:

  • What is responsible for the sound you heard and the odor you smelled?

  • What elements do you think the gas is made of?

  • Ask students if they think that gas can be utilized as a source of fuel to run industries, vehicles, or even farming operations?

Invite groups to share their responses with the class.

Clarify for students that you placed manure, water, and paper in the bottle and left it undisturbed for 4–5 days. Express to students that the  paper serves as a food source for tiny organisms that are in the manure. As the organisms decompose the paper, they produce a gas. The water assists in the decomposition process. 

Display slide 6 and review the instructional strategy What Did I Learn Today? Ask students to use the same paper they made their original observations on to write down on explaining what they learned from this activity. Consider using their responses as an exit ticket. 

Explore

Place students into groups of four and pass out the attached Biogas Digester Experiment handout to each student. Explain to students that they will be building mini biogas digesters using small water bottles. Their challenge is to design experiments that increase the rate of decomposition and gas production in the “burping bottles.”

Display slide 7 and review the guiding question: "Can you increase the rate of decomposition in the burping bottles?"

Move to slide 8, distribute the attached Sample Biogas Digester Experiment handout to each group. Tell students that a hypothesis is an educated guess or testable statement about what you think will happen in an experiment. Direct students' attention to the sample hypothesis and review it. Allow students time in their groups to come up with and write down their own hypothesis in the space provided on their Biogas Digester Experiment handout. 

Transition to slide 9 and provide an overview of the possible digester inputs. Explain that students can adjust both the amount and type of materials used—such as the kind of manure, liquid, or carbon source. Offer examples of substitutions: apple cider instead of water, or plastic or oatmeal instead of paper. Students must also determine how they will measure both decomposition rate and gas production.

Students measure the rate of decomposition by recording the mass of the bottles every few days. They also measure the amount of gas produced by attaching a balloon to the top of each bottle. As decomposition happens, gas inflates the balloon, and students can measure its circumference. 

Tell students to ensure that the balloons remain sealed until the end of the experiment to avoid gas loss and contamination. 

There are numerous experiments students can conduct with the mini biogas digesters. The primary goal is for students to practice experimental design while observing how digesters break down organic materials and produce gas. Students will use their handouts to write a lab report following the components listed in the example provided. In the Evaluate phase, they will create posters and share their data with the class. If needed, graph paper is also attached to the lesson.

Explain

Move to slide 10 and review the 3-2-1 instructional strategy. Ask students to take out a piece of paper and complete this strategy while they watch a video. 

After the video is over, invite a few students to share their 3-2-1 responses with the class.

Next, direct students to read the article: “Aerobic and Anaerobic Biodegradation."

Display slide 11. After students have finished the reading, they should answer the questions below with their group. 

  1. What gas is produced in your bottles?

  2. What happens to the gas when you release it from the bottle?

  3. Is that gas beneficial for the environment?

  4. How could we prevent the gas from entering the atmosphere?

After students answer the questions in their groups, have a brief class discussion about each question, calling on groups to share their responses to the questions.

Extend

Linked below are four articles that cover how biogas digesters have been used at farms and homes, and how scientists hope to use the methane produced as fuel for space travel. 

Display slide 12 and review the Jigsaw instructional strategy with students. Assign each student in the group an article to read. After the students have read the article, they should come together as a group and discuss their articles.

  1. Biogas Digester

  2. Chapter 7 - Biogas Digesters

  3. Human Poop-Powered Rocket May Fly Man to the Moon in the Future

  4. Manure Digester Means Nebraska Farm is Powered by Pigs

After discussing the articles and reflecting on what they've learned in this lesson so far, move to slide 13 and ask groups to brainstorm ideas for ways that biogas digesters could be used in or around their communities. Tell students to keep in mind that they will create a visual presentation for the class based on what they decide. 

Once groups have chosen their focus, transition to slide 14 and review the Two-Minute Paper instructional strategy. Ask each group to take out one piece of paper and work together to respond to this prompt:

  • In one paragraph or less, explain where a biogas digester is needed in our community, why it will be useful in that location, and how it will be constructed. 

Collect the responses as exit tickets. Let students know you will review their ideas before the next class period and confirm whether they may proceed with their presentations or need to revise their proposals.

Evaluate

Display slide 15 and pass out the attached Poster Rubric to each group. Tell students that they will be creating a poster with their group and review the requirements with them on the slide. Then, ask them to look at the  poster rubric and review it with them. Pass out a piece of poster paper to each group and allow time for students to complete the task. 

After the poster is created, ask students to place their posters around the room. Move to slide 16 and review the Gallery Walk instructional strategy. Ask that one student from each groupstand by the poster to clarify any questions the other students may have about the experiment. The rest of the groups should move around the room to observe and ask questions about other experiments.

Once you have approved each group’s experiment proposal, they can begin constructing their presentations and doing any necessary research.

Display slide 17 and pass out the attached Presentation Rubric to each group.  Review the rubric and guidelines on the slide with students. Tell each group to add what they learn from their experiment into their presentations about using a biogas digester in the community. Explain to students that each member of the group should speak for 2 minutes, except for the group member who stood next to the poster during the gallery walk and answered questions, because their presentation requirement for this assignment is complete. However, they still have to contribute to the final project by researching, providing ideas, or helping build the final presentation.

Resources

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K20 Center

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Standards

ACT College and Career Readiness Standards - Science (6-12)
IOD403: Translate information into a table, graph, or diagram
SIN503: Determine the experimental conditions that would produce specified results
EMI502: Determine whether presented information, or new information, supports or contradicts a simple hypothesis or conclusion, and why
Next Generation Science Standards (Grades 9, 10, 11, 12)
HS-PS3-1: Create a computational model to calculate the change in the energy of one component in a system when the change in energy of the other component(s) and energy flows in and out of the system are known.
HS-PS3-3: Design, build, and refine a device that works within given constraints to convert one form of energy into another form of energy.
HS-LS2-7: Design, evaluate, and refine a solution for reducing the impacts of human activities on the environment and biodiversity.
Oklahoma Academic Standards for Science (Grades 9, 10, 11, 12)
PS.PS3.1: Create a computational model to calculate the change in the energy of one component in a system when the change in energy of the other component(s) and energy flows in and out of the system are known.
PH.PS3.3: Design, build, and refine a device that works within given constraints to convert one form of energy into another form of energy.
EN.LS2.7: Design, evaluate, and refine a solution for reducing the impacts of human activities on the environment and biodiversity.

Facilitator Resources

Click on a file type icon to download an attachment.

  • Lesson Slides—Microbes and Manure Biofuel

Learner Handouts

Click on a file type icon to download an attachment.

  • Biogas Digester Experiment—Microbes and Manure = Biofuel
    • English
    • Spanish
  • Poster Rubric—Microbes and Manure = Biofuel
    • English
    • Spanish
  • Presentation Rubric—Microbes and Manure = Biofuel
    • English
    • Spanish
  • Sample Biogas Digester Experiment—Microbes and Manure = Biofuel
    • English
    • Spanish

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