Soda Energy Pyramid Activity

Give each lab group this tray setup at their tables.

Learning about energy flow in an ecosystem is a basic lesson in every biology classroom. I always wondered how I could make this unit more interesting or hands-on. Well, I think I might have found the lab that does just that. I got this lab from a teacher I work with. I like it because it gives a visual representation on just how energy is lost as it is passed to one organism to another in a food chain. I think this activity is a must try in your biology class-especially for middle schoolers. It’s easy to set up and the materials for it are inexpensive. Let's dive into it.:)

Materials you will need for each lab group:

Beaker

Pipette or medicine dropper

Graduated cylinder

Small clear plastic cup

Small plastic cup of any color

Medicine plastic cup (three per group)

Soda Energy Pyramid Worksheet (FREE)

Prior to the lab, give students a overview on how energy transfer happens in an ecosystem, by reviewing the 10% rule using an energy flow pyramid. In a food chain, energy flows from the sun to the producers, from producers to primary consumers, from primary consuners to secondary consumers, from secondary consumers to tertiary consumers, and last, from tertiary consumers to quaternary consumers. Energy must be transferred through an ecosystem to support life at each trophic level.  Each level in a food chain, or step in an energy pyramid, is called a trophic level.

Overview

Energy from the sun is captured by plants and used to make food in a process called photosynthesis. Some of this energy is used to carry on the plants' life activities. The rest of the energy is passed on to the next level of a food chain. Energy from plants (producers) is transferred to primary consumers, and from the primary consumers to secondary consumers and so forth as energy flows up the pyramid. What students need to know is that 90% of energy is lost at EACH trophic level. This means that only 10% of the energy at each trophic level is passed on to the next trophic level in a food chain or food web. Because there is more available energy at the bottom of an energy pyramid than at the top, an ecosystem can support more producers than consumers, and even less of the top predators.

Where does the 90% of energy loss go? It is lost as thermal energy (heat)-used for life processes such as growth, respiration, and reproduction. In this lab, students will use soda and various containers to learn about this 10% rule. 

Before the lab, review the energy pyramid with the class and using a table similar to the one showed here, walk them through how to fill out the data for this table:

In an ecosystem, energy flow is often meausred in kilojoles. In this lab the sun's energy will be represented by 1000 mL of soda. Using the 10% rule, you will walk students through the math that helps them find the next number in the table.

For example, if we start with1000ml of soda (producer level), you will then multiply 1000 x .10 = 100ml or simply move the decimal one place to the left to go from 1000 to 100, whichever method you prefer. Keep doing this math with each new answer you get until you get to the quaternary trophic level in the table.

WHO is the SUN in this lab? You! You, the teacher, will be the sun since you are the CENTER of your classroom, so let students know that you are starting the lab with 1000ml of soda, and since only 10% of the energy is transferred to each trophic level, you will fill each producer cup at each lab table with 100ml (10% of 1000) of soda. Once students fill out the data table above, they can proceed with the lab. You may want to walk them through it step by step to ensure it goes smoothly. To start, show them a beaker with 1000ml of soda to represent the sun's energy.

To begin the lab, assign students to groups of five. Assign each group member an organism to pretend to be. The organisms in this lesson are a plant, grasshopper, frog, snake, and an eagle. You may print out the labels for these-they are in my free worksheet packet. Give the labels to each member of the group.

EACH student will receice a specific type of cup and label, depending on the role they play in the lab. For example, the student who is the producer will have a clear cup and the PRODUCER label. The soda in each cup will represent how much energy is transferred to them from the previous trophic level when one organism eats another organism.

To Begin:

Who gets what container?

1. The producer gets a clear, regular size cup.

2. The grasshopper gets a colored, regular size cup.

3. The frog, snake, and eagle each get a plastic medicine or condiments cup, like shown below (So, you will have three of these in your tray set up).

Round 1:

Tell the producer that you, the sun, already transferred 10% of your energy to them, which is why the CLEAR CUP in their tray already has 100ml of soda already in it. This will represent the energy is the PRODUCER trophic level.

 Round 2:

Tell the student who is the grasshopper to use a pipette to remove 10ml of soda from the producer's cup and add this to the graduated cylinder so it is at the 10m line. Then they will pour this amount of soda into the grasshopper’s cup.

Round 3:

Next, the student assigned the frog will take a pipette and remove 1ml of soda from the grasshopper’s cup and place it in their medicine cup (This will be about 2 of small drops from the pipette).

Round 4:

 The student who is the snake will use a pipette to take a tiny amount (1ml) of soda from the frog's up and transfer it to their medicine cup. It is hard to take out that much, so 2 very small drops using the pipette should be fine for the demonstration.

Round 5

The student who is the eagle will use a pipette to remove an even smaller amount (.01ml) of soda from the snake's cup and transfer it to their medicine cup. This will be difficult, so they can just do one small drop for the demonstration.me my worksheet for this lab if you want.

After the lab, students should be able to see just how little energy is left at the top of the energy pyramid (top of the food chain in an ecosystem). Lastly, they can work on the post lab worksheet below. It is available as a digital download in my Tpt store.