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Classroom Activity: Food Chain Checkers - Windows to the Universe

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Food Chain Checkers

Summary:
Students play a game that models dynamics of a simple food chain, then they improve the model by making their own rules that better account for the ways that food chains work. Materials:
(For each group of four)
  • Checkerboard
  • 24 Diatom game pieces
  • 24 Copepod game pieces
  • 24 Herring game pieces
  • 24 Whale game pieces
  • Food Chain Checkers worksheets for each student (double-sided)
  • Optional Graphing Populations over Time worksheet for each student (double-sided)
  • Colored pencils for optional graphing activity

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Source:
Windows to the Universe activity by Lisa Gardiner
Grade level:
5-9
Time:
15 minutes prep time
One or two 50-minute class periods
Student Learning Outcomes:
  • Students will learn that food chains connect organisms within an ecosystem.
  • Students will learn that food availability can cause changes in population size.
  • Students will learn that the size of populations in a bal­anced ecosystem stay somewhat constant over time.
  • Students will learn that models can be used to represent the natural world and that improvements to models al­low us to more accurately represent natural conditions.
Lesson format:
Hands-on activity with follow-up group discussion

National Standards Addressed:

  • 5-8 Content Standard C: Populations and Ecosystems
  • 9-12 Content Standard C: Interdependence of Organisms
  • Benchmarks: 5A/5 and 5E/2

DIRECTIONS:

Preparation:

  1. Copy and cut apart game pieces from the template (last page). You will need two copies of the template for each group of students.
  2. Copy Food Chain Checkers worksheet (pages 4 and 5) and, if you wish, the optional Graphing Populations over Time worksheet (pages 6 and 7) for a more quantitative activity.
  3. If needed, a checkerboard can be downloaded and printed on 11 x 17 paper from Windows to the Universe at: www.windows2universe.org/teacher_resources/gameboard.pdf

Directions:

  1. Have students read the description of food chains on the first page of the Food Chain Checkers worksheet.
  2. Discuss the main characteristics of food chains as a group. Introduce the game to students and review the rules (second page of Food Chain Checkers worksheet). Tell students that for this activity they are each playing the role of a different species in a food chain. They will travel around the game board trying to catch their prey (by jumping over it) and avoiding predators.
  3. Introduce the concept of models to students. This game is a simple model of an aspect of the natural world. Scientists use models to help us understand how the world works. They try to make models as accurate as possible, so they are always thinking about how to improve a model to make it better represent the real world. As they play round one of the game, ask students to think about how they will improve the model. What ecological conditions could be better represented? How would you modify the game to take them into account?
  4. Student groups play round one of the game following the rules on the worksheet and then answer the questions on the bottom of the worksheet. For a more quantitative approach, and to exercise graphing skills, have students also fill in data about population size in the Graphing Populations over Time worksheet. (This will add more time to the length of this activity.)
  5. Discuss as a group how the game is not like a real food chain. The main points that students will hopefully pick up upon are listed below, however, this is not a complete list. Encourage students to brainstorm others too.
    • Without the Sun there is no way for the diatoms to reproduce.
    • Copepods, herring, and whales initially have populations of the same size and need the same amount of food to reproduce. This is not like the real world.
    • The individuals never die unless they are eaten (i.e., there is no natural death.)
  6. Have student groups devise more game rules to take into account the problems with this model and make the model better. Have them write out the revised rules and the real world situation that it addresses.
  7. Students play round 2 of the game using their modified rules. If data collection and graphing was done in round 1, then have students repeat the process and compare graphs.
  8. Discussion - Student groups report on how they revised the model and whether they were able to maintain healthy populations of all members of the food chain.
  9. If time permits, let student groups revise rules again and play one more time or use the game as a model to explore what would happen if there were an environmental change (e.g., whales killed, diatom bloom, over fishing).

BACKGROUND INFORMATION:

A food chain is a group of living things that depend on one another for energy. Energy is passed along the food chain. All living things need energy. Animals and many single-celled protists get the energy they need from the food they eat. Plants and algae get the energy they need from the Sun. Bacteria get energy in many different ways.

The living thing at the bottom of almost all food chains is something that, by photosynthesis, makes its food using sunlight, water, and carbon dioxide - a plant for example. At the other end of food chains is a top predator, an animal that eats other animals and whom nothing else eats.

A simple food chain may include:

  • Producers: via the process of photosynthesis they make food inside their bodies using sunlight, water, and carbon dioxide. (Note: At places without sunlight, like deep sea vents, producers make energy via chemosynthesis.)
  • First-order consumers: A species that eats only producers, also known as an herbivore.
  • Second-order consumers: A species that eats herbivores, a type of carnivore
  • .
  • Third-order consumers: A species that eats carnivores. If it has no natural predators, it is known as a "top predator".
The four listed above make up most simple food chains. However, there are some living things that have different patterns of eating. Living things that eat both producers and animals are called omnivores. Humans are omnivores. Omnivores are often a part of several different food chains. Living things that eat dead and decaying life are called decomposers. Many types of bacteria and all types of fungi are decomposers.

In every food chain there are more individuals at the bottom than at the top. Each first-order consumer needs to eat several producers to survive. Each second-order consumer needs to eat several herbivores to survive. So the number of producers and herbivores must be higher than the number of second- and third-order consumers.

This game uses a simple marine food chain example with four species:

  • Diatoms: These producers are some of the most prolific in the world's oceans. Diatoms are algae and are a part of the phytoplankton ("phyto" means they do photosynthesis and "plankton" means they float in the water.)
  • Copepods: these little animals are first-order consumers and a part of the zooplankton ("zoo" means animals). They belong to a group of invertebrates called arthropods and are related to shrimp.
  • Herring: These fish are second-order consumers. They are common in the North Pacific and North Atlantic Oceans. When eating, they swim with months open filtering out zooplankton like copepods from the ocean water.
  • Orca: Also known as killer whales, Orcas are third-order carnivores and the top of this food chain. They eat herring in this food chain. Orcas also eat many other animals, making them a part of several other marine food chains too. Because other animals do not eat them, Orcas are top predators would only die of old age (if they were not affected by humans.)
For more information about these species, please see the links in the Resources section below.

Also note that living things are actually connected to many others through a food web, a collection of interconnected food chains. They are also connected to each other in other ways too. This means that thinking about a single food chain is a bit simplistic, however, food chains are important building blocks to learning about ecosystem science.

Use of Models in Science

Models are important and useful tools in geoscience education. It is important to understand both the utility and the limitations of models. Before using a model, talk to your students about the usefulness of models, but also the limitation of models. Encourage them to come up with examples. "Models can easily be misused. In fact, a frequent cause of students' science misconceptions is confusion between characteristics of a model and the characteristics of the real thing it represents.

Four questions, used routinely during instruction, can help prevent these misconceptions:

  • How does this model work the same as what it represents?
  • How does this model work differently from what it represents?
  • What are the strengths of this model? The weaknesses?
  • How does this model compare and contrast with what it represents?*
(*From Understanding Models in the Earth and Space Science - Steven W. Gilbert and Shirley Watt Ireton - 2003 NSTA Press)

Improving models is an ongoing process for geoscientist who work with models of our planet and its processes. Usu­ally, new learnings about how the Earth works lead to model improvements. In this activity, students are encouraged to modify the model so that it better represents the real world situation. Making sure that students understand the analogy of the model to the real world as they make new rules is essential for turning a simple game into a model of ecological processes.

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