Are you looking to liven up your intro unit on the characteristics of life with an Is Yeast Alive lab? Well then get ready to learn about an experiment that will have your students bubbling with excitement (literally!). This experiment involves a little yeast, a sprinkle of student inquiry, and a whole lot of fizzy fun. This hands-on lab is a fantastic way for students to design, conduct, and analyze an experiment to determine if that packet of yeast hiding in the back of your cabinet is truly alive!

Before we unleash the yeast upon the lab, let’s set the stage for scientific exploration. Start by kicking things off with a good old-fashioned brainstorming session. Ask your students, “What are the characteristics of life?” Guide them towards a list that might include things like organization, growth, development, reproduction, energy use, response to stimuli, and adaptation.

Introducing The Experiment To The Class

First you will want to introduce the star of the lab – yeast! This single-celled fungus is readily available (often hiding in your pantry!) and a fantastic model organism. Why? Because yeast exhibits many of the characteristics of life in a simple and easy-to-observe way – perfect for our scientific investigation. Briefly explain to your students that yeast is a single-celled organism and that we’re about to put its “aliveness” to the test. 

This lab flips the script on traditional experiments. Instead of a predetermined procedure, we’re empowering students to design their own! Challenge them to develop a question that relates to one of the characteristics of life we discussed. Here are some prompts to get their creative juices flowing:

• Does yeast need energy to function? (This is a great starting point!)
• Does yeast need a specific temperature to function?
• Does yeast grow faster with or without a certain nutrient?

Once students have a burning question, it’s time to create a hypothesis. This is their educated guess about what they expect to see based on their understanding of the chosen characteristic of life. For example, if the question is “Does yeast need energy to function?”, a hypothesis could be: “If yeast is given sugar (an energy source), it will produce more gas than yeast without sugar.”

Is Yeast Alive Lab Materials List:

• Safety Goggles (always a must!)
• Disposable Gloves (optional, but good practice)
• Small Flasks or Bottles (like 250ml Erlenmeyer flasks or 16-ounce water bottles)
• Balloons
• Measuring Spoons and Cups
• Warm Water (around 35°C or 95°F)
• Active Dry Yeast Packets
• Sugar
• Permanent Markers
• Tape
• Lab Notebooks

Time to Begin the Is Yeast Alive Lab

Now that the brainstorming is done, let’s get down to the nitty-gritty of scientific design (check out these FREE experimental design posters I use in my class). Explain the concept of variables – the factors that can change in an experiment. In this case, the independent variable is the temperature (warm or cold). The dependent variable is the amount of carbon dioxide gas produced (measured by bubble formation). The control variable is everything else that’s kept the same between the groups (type of yeast, amount of sugar solution, etc.).

Have your students design a step-by-step procedure for their experiment. This might involve using balloons to capture the carbon dioxide gas, comparing the amount of gas produced in warm and cold solutions, and recording their observations over a set period.

It’s time to roll up those sleeves and get those beakers bubbling! Of course, discuss basic lab safety protocols before your students set off on their yeast-busting adventure. Students get to work following their designed procedures. This is where the excitement builds as they mix their sugar solutions, add the yeast, and witness the bubbling magic (hopefully!).

Encourage students to record their observations throughout the experiment. This could involve measuring the height of the balloons in each group at regular intervals or noting any visible changes in the yeast or solution. Ask them to record their observations in their lab notebooks, including:

• Are there any changes in the balloons? Do they inflate? If so, which ones?
• Is there any bubbling activity in the flasks? If so, is it more pronounced in some flasks compared to others?
• Are there any differences between the flasks?

Analyzing the Results

Once the experiment is complete, it’s time for your budding scientists to analyze their data. Have students compile their data in tables or graphs. This visual representation allows them to compare the amount of carbon dioxide gas produced in the warm and cold solutions.

Guide your students to formulate a conclusion based on their results. Did their findings support their hypothesis? If so, what does this tell them about the characteristics of life that yeast might possess? If not, what alternative explanations could there be?

Discussion Of Results From The Is Yeast Alive Lab

This lab can be a springboard for further discussion and exploration. You can ask questions like:

• What other characteristics of life does yeast exhibit? (Growth, metabolism, etc.)
• What would happen if we used a different type of sugar?
• How does temperature affect yeast activity?

Explain the science behind what happened in the lab. Explain that when yeast encounters sugar, it undergoes a process called cellular respiration. During this process, the yeast breaks down the sugar molecules to release energy. One of the byproducts of cellular respiration is carbon dioxide gas. This gas is what inflates the balloons!

The yeast experiment doesn’t have to end with bubbling balloons. You can extend learning by discussing the concept of error in scientific experiments. What factors might have influenced the results? How could they improve the design of their experiment next time? Challenge students to create a model of a yeast cell, highlighting the different organelles and their functions.

Take things a step further by exploring the process of fermentation, where yeast consumes sugar and produces carbon dioxide and alcohol. This can lead to exciting discussions about the role of yeast in bread baking and alcoholic beverage production.

Related Articles and Resources:

• Characteristics of Living Things Lesson
• Are Viruses Alive – CER Activity
• Pond Water Characteristics of Life Lab

The Is Yeast Alive lab isn’t just about inflated balloons and bubbling concoctions (although, let’s be honest, those are pretty fun!). It’s about empowering students to take charge of their learning, grapple with scientific concepts, and discover the fascinating world of living things.

So, next time you’re teaching about the characteristics of life, ditch the traditional lecture and embrace the bubbling fun of a student-designed yeast experiment. You might just be surprised by the depth of learning and the enthusiasm the Is Yeast Alive lab ignites in your classroom!