Invasive Species Council of British Columbia

For Educators

Unit: We Care for the Land – Activity 4: Ecosystem Webs

Grade: 4 to 6

Duration: 45 minutes

Setting: Indoor/outdoor

Subject: Science

Physical Activity: No

Students take on the identity of a living or non-living organism in their local ecosystem and then see how everything is interconnected by creating an ecosystem web. The potential impacts of invasive species on the ecosystem web are considered.

This is the fourth activity in the Grade 4-6 Learning Resource, We Care for the Land and Prevent the Spread of Invasive Species. Please see the Overview for this resource for more information, including the lesson sequence.

This resource was created through the financial support of the Provincial Intermediate and Middle Years Teachers’ Association (myPITA).

Learning Objectives

By participating in this activity students will: 

  • Be able to name several native species and an invasive species in the region
  • Understand that living and non-living organisms interact with and depend upon each other in their ecosystem
  • Understand how an invasive species could harm native species in an ecosystem
Inquiry Questions
  • How is an ecosystem like a web of interconnections?
  • What is the role of humans in the web of life? How can we help to maintain the web?
BC Curriculum Links

Science Big Ideas

  • All living things sense and respond to their environment (Grade 4)
  • Multicellular organisms have organ systems that enable them to survive and interact within their environment (Grade 5)
  • Multicellular organisms rely on internal systems to survive, reproduce, and interact with their environment (Grade 6)

Science Content

  • First Peoples concepts of the interconnectedness in the environment (Grade 5)

Science Curricular Competencies

  • Experience and interpret the local environment (Grades 4-6)
  • Identify some simple environmental implications of their and others’ actions (Grade 4); Identify some of the social, ethical, and environmental implications of the findings from their own and others’ investigations (Grades 5-6)
  • Demonstrate curiosity about the natural world (Grade 4)
Materials
  • Ball of twine or rope
  • Safety pins, clothes pins, or string & lanyards to attach species photos to students

Documents to Download

Or make your own set of cards (enough for one card per person in the group) using images of species of your choosing. Include a diversity of native organisms (plants, fungi, and animals) from your region. You can also include some non-living things (sun, soil, water, rocks, air, dead tree, etc). See the Additional Resources section for suggested sources of images.

Background Information

An ecosystem is a community of living organisms, such as plants, fungi, and animals, interacting with each other and their non-living environment (temperature, moisture, soil, air, and sunlight) in a specific area. The living (biotic) and non-living (abiotic) components of an ecosystem are interconnected. Ecosystems can be very large or very small, such as an isolated tidepool or an expansive forest.

Every part of an ecosystem depends on every other part, directly or indirectly. For example, plants need sunlight and water to photosynthesize. Some animals eat plants, or need plants for their shelter. A change in temperature in an ecosystem can affect what plants grow there, having ripple effects on other organisms, including the animals that depend on those plants for food and shelter.

Invasive species spread and take over, causing great impacts on ecosystems. Invasive species can have direct impacts by eating native species, or indirect impacts by outcompeting them for food, shelter or space. For example, American bullfrogs are the largest frogs in North America and they eat anything that can fit in their mouths, including fish, insects, and even ducklings. Invasive species can also impact abiotic factors in an ecosystem.

For example, hawkweeds release toxins into the soil, preventing other plants from growing and Eurasian watermilfoil, which can clog waterways impacting water flow and descreasing levels of dissolved oxygen, which can cause fish die-offs.

By being more aware of all of the many interconnections in an ecosystem, people can play a positive role by treating nature with respect and helping to prevent negative impacts to the web. People can also play an active role in preventing the spread of invasive species in their community.

Preparation
  • Print the Ecosystem Web Cards (Materials section) or images of a variety of native species that are found in your region (See the Additional Resources for sources of images.) There should be one card per student.
  • In addition, download and print at least one of the Invasive Species Teaching Cards. Select a species in your region that might be familiar to students or one that you would like them to learn more about. If you aren’t sure which one to select you can learn more about the invasive species in your region by clicking on the BC Regional Invasive Species Map.
Procedure
  1. Read this quote from Chief Si’ahl (Seattle) from 1854 and discuss: “Humankind has not woven the web of life. We are but one thread within it. Whatever we do to the web, we do to ourselves. All things are bound together. All things connect.”  What does this mean? How are we connected? What is a web of life?
  2. Tell students that we are going to build a web of life (an Ecosystem Web) using a ball of rope or yarn to demonstrate the interconnectedness between all organisms.
  3. Pass out an Ecosystem Web card to each person. Give everyone their new “identity” and have them gather in a large circle, facing towards the centre. Have them turn to their nearby neighbours and introduce themselves to each other.
  4. Tell everyone that in an ecosystem everything is interconnected. Now, with our new identities, we are going to explore how we are all connected to each other in this ecosystem. Assign one student (or teacher) to be in the centre of the circle as the sun- the main source of all energy on Earth.
  5. Ask if anyone can think of how they are connected to the sun (e.g. plants are primary producers that photosynthesize using the sun’s light to form sugar as energy; cold-blooded animals like reptiles need the sun to thermoregulate, etc.). Pass one end of the ball of rope to someone who can describe their connection to the sun. Tip: Don’t throw the ball of rope or it will quickly get tangled! One person (an adult or responsible student) has the role of joining others into the web by passing the other end of the rope from one person to the next. Once someone joins the web they keep hold of the rope. Everyone should remain standing in a circle.
  6. Continue to link everyone together by asking the rest of the group if anyone can describe their connection to the person with the rope. Consider the food chain (what they eat or what eats them) and their habitat needs (such as where it nests, shelters, or spends part of its life cycle). For example, the sun provides energy to the maple tree; the squirrel eats the maple seeds, the owl eats the squirrel, the fungus decomposes the tree, the woodpecker nests in the tree.
  7. Build the web. Continue passing the rope and stating relationships until everyone is connected in a giant web. Students can collaborate and offer suggestions if someone is stuck and doesn’t know how they might be connected to those already in the web.
  8. Once everyone is connected in the web, direct students take a step back to create tension in the rope, representing that all things in the ecosystem are interconnected and interdependent.
  9. Ask one student to gently tug on the rope, and if they feel a tug, they should tug back in response. This demonstrates how a change in one part of the ecosystem can affect the entire web. 
  10. Now introduce an invasive species to the web. Select and print an invasive species from the Invasive Species Teaching Cards that students may be familiar with that could be in your area. Select one student to give up their old identity as a native species and become the invasive species, describing how the invasive species arrived, such as it was planted in a garden and escaped from cultivation, or it was a pet that was released.
  11. Students now consider this change in the ecosystem web and how it impacts them. For example, if the invasive species is yellow flag iris, a wetland plant that takes over shorelines, cattails would be displaced. Western painted turtles would also be impacted because the yellow flag iris prevents them from moving between their nest sites on shore and the water. Any species dependent upon the cattails and turtles would then also be out. Impacted native species should sit down while holding the rope, creating tension on the rope.
  12. Anyone who feels the tug of the rope – representing the impact of the invasive species- should also sit down. See what happens to the web.
  13. Ask students for actions that could be done to help restore the web, such as by removing the invasive species or preventing them from arriving in the first place. End by restoring the web and having everyone rejoin, standing in a circle.
Reflections and Assessment
  • Refer back to Chief Si’ahl’s quote: “Humankind has not woven the web of life. We are but one thread within it. Whatever we do to the web, we do to ourselves. All things are bound together. All things connect.”  Do you agree or disagree with these statements?  Give examples to support your opinion.
  • What are some other threats that could threaten the ecosystem web? Consider habitat loss, overfishing, pollution, or forest fires. What are some ways that the web can be protected?  (Habitat protection, beach clean ups, other stewardship action.)
  • What is the role of humans in the ecosystem web? How can we play a positive role in maintaining and restoring the ecosystem web?
  • How has an ecosystem in your area changed since colonization?
Accessibility and Adaptations
  • This activity can be done indoors or outdoors, sitting or standing.
  • For active groups, you could spread out and have people run or move around more. People could be connected into a web by throwing a ball or frisbee and then have them join together and link arms.
Extensions
  • Bring it outside! Go outdoors to look for species from your ecosystem web, or to look for interactions between organisms and the environment.
  • Learn more about the invasive species found in your community and what people are doing to take action to prevent their spread.
Connections to First Peoples’ Perspectives

The interconnectedness of everything in nature is a concept central to Indigenous cultures. Many Indigenous languages have a word or expression that describes this interconnectedness. For example, Nuu-Chah-Nulth (Central and Northern Coastal BC) say Hishuk ish ts’awalk, “everything is one and all are connected”. The Haida (Haida Gwaii) say Gina ‘waadluxan gud ad kwaagid, “Everything depends on everything”, and the Secwepmc (Shuswap, South-Central Interior) say Kweseltnews “We are all family”. (Secondary Science First Peoples Teacher Resource Guide, FNESC/FNSA 2019 http://www.fnesc.ca/sciencetrg/)

Additional Resources

Native Species of BC

Images and species information to make your own ecosystem web cards

British Columbia Ecosystems

Invasive Species