Invasive Species Council of British Columbia

For Educators

Unit: We Care for the Land – Activity 7: Weed Out the Invasives

Grade: 4 to 6

Duration: 30 minutes

Setting: Indoor/outdoor

Subjects: Physical and Health Education, Science

Physical Activity: Yes

This activity will help students learn the similarities and differences between native and non-native species through an active relay game. Teams practice identifying common plants from photographs and “weed out” the invasives to help protect native plant biodiversity.

This is the seventh 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 and identify some native, introduced, and invasive plants found in the region.
  • Understand the environmental harm that invasive plants can cause.
  • Understand that we can all play our part to prevent the spread of invasive species, including by being “PlantWise” (e.g. not planting invasive plants in gardens or dumping garden waste)
Inquiry Questions
  • What are some invasive garden plants in my area?
  • How do invasive plants cause harm?
  • How can people help prevent the spread of invasive plants?
BC Curriculum Links

Physical and Health Education Big Idea

  • Daily physical activity enables us to practice skillful movement and helps us develop personal fitness (Grades 4-6)

Science Curricular Competencies

  • Identify some simple environmental implications of their and others’ actions (4); Identify some of the social, ethical, and environmental implications of the findings from their own and others’ investigations (5-6)
  • Experience and interpret the local environment (4-6)

Social Studies Curricular Competencies (Cause and Consequence)

  • Differentiate between intended and unintended consequences of events, decisions, or developments and speculate about alternative outcomes (Grades 4-6)
Materials
  • Photographs of native, non-native (not invasive) and invasive plants in BC, such those in the Grow Me Instead snapshot booklet. See the Preparation section for other sources of images.
Background Information

Invasive species are one of the greatest threats to biodiversity. Most invasive species are introduced to new places by people, either accidentally- such as an aquatic organism transported in ship ballast water or an insect or plant hitching a ride on clothing- or intentionally, such as a pet let loose. Most exotic plants in BC were intentionally introduced for their attractiveness as garden plants. Unfortunately, some of these far-away species end up becoming invasive due to a lack of predators and pathogens in their new home. Invasive species spread rapidly and can have severe impacts on our native ecosystems, way of life, and economy.

Some invasive plants are hard to control in the garden, such as yellow archangel or English ivy. Others, such as English holly or butterfly bush, may not appear to be spreading in the garden but their seeds can be dispersed to new places by wind or birds, where they can quickly establish and spread.

Many invasive plants are still sold and planted today. The best way to play our part and be responsible gardeners is to be “PlantWise”. PlantWise is provincial program designed to support gardeners and the horticulture industry to make the transition to become invasive species free. We can all be PlantWise by:

  • Learning about what plants are invasive in the garden and to avoid buying, trading, or planting them. See the Grow Me Instead resource to learn which invasive plants are most problematic in the horticulture industry, and which alternative species you can grow instead!
  • Avoiding wildflower seed mixes, which often have a majority of invasive plants in their contents.
  • Disposing of garden waste with care. Don’t dump soil or plants on roadsides or by parks where invasive seeds can establish and spread. In most municipalities, invasive plants should be bagged and disposed of in the trash rather than composted.

Definitions and Terms

Invasive species are non-native organisms that have been introduced from other areas, either intentionally or accidentally, where they cause harm to the environment, economy, or society. Without their natural pathogens and predators, they are capable of moving aggressively into an area, and monopolizing resources such as light, nutrients, water, and space to the detriment of other species. Invasive species threaten natural ecosystem functions, species biodiversity, food security, human health and safety, and economic development. Not all introduced species thrive and become invasive when they are brought to a new place.

Native species are living organisms that are found in their location without assistance from people. Native species have typically evolved in a place for thousands of years (such as since the last ice age) where they are part of a balanced ecosystem and part of a food web including their predators, prey, and pathogens. Native species in North America are those that already existed here at the time of European colonization.

Introduced or Non-native species, sometimes called exotic or alien species, are those that have been introduced to a new location, intentionally or unintentionally, to which they did not evolve and are not typically found. Not all introduced species are invasive!  Some non-native species may be invasive, spreading and causing negative environmental, economic, or social impacts, while others may not survive or thrive without being cared for by people.

A weed is any plant whose presence is undesirable to people in a particular time and place, such as in a garden or lawn. A weed could be either native or non-native. For example, a native willow seedling growing in your garden is a weed if you don’t want it there. A weed is not the same as an invasive plant. An invasive plant is a plant that when transplanted from its native habitat, grows aggressively, outcompeting and displacing desired vegetation and causing harm to the environment, economy, or human health and safety.

A Noxious Weed is an invasive plant that is regulated by the BC Weed Control Act. This Act imposes a duty upon land occupiers to control these provincially designated, aggressive and destructive species.

Preparation
  • Source about 30-40 printed photos of regional native, non-native, and invasive plants, with at least half being invasive plants. Ideally have approximately the same number of invasive plants as there are people in the group.
  • A quick way to source photos is to make two colour copies of the Grow Me Instead snapshot booklet. Keep one copy as your “Answer Key” and cut out the photographs from the other copy to use in the game (omit the names of the plants and information if it is invasive or not!). Try to cut the pictures out so that all the plant images are approximately the same size so that students don’t discover that all the larger photos are of invasive plants. You can do this by cutting the invasive species into smaller sizes or by making photocopy enlargements to increase the size of the native/non-invasive plants.
  • Other native, introduced, and invasive plant images could be sourced from:
    • photographs of plants from your schoolyard or neighbourhood
    • seed catalogues
    • calendars
    • Sierra Club BC’s EcoMap (Native species)
    • Grow Me Instead website (ISCBC)- to access more and larger photos than what is on the Grow Me Instead snapshot booklet.
    • Regional invasive species map (ISCBC)- select your region to see some common invasive plants and animals found there. You can also find your area contacts on the map and visit their websites for more regional invasive species information and images.  
    • From Here From Away Species Cards (ISCBC) for native, introduced, and invasive animals and plants.
  • Select a few invasive plants that you will share after the activity, including how they got to BC and the harm that they cause. If you aren’t sure which plants to select, try one or more of these, all of which were originally introduced to BC as garden plants and now are big problems!
Procedure
  1. Set up a large open space in the classroom, gym, or outdoors.
  2. Divide the group into several (2-4) teams.
  3. Lay out all the photos on a table or on the ground on the opposite side of the space.
  4. Explain that the object of the game is to go to the site (give it the name of a local park!) and do a weed pull, removing only the invasive plants. Review definitions of native, non-native/introduced/exotic, and invasive, (see the Background section) and share some examples. Remind students that not all non-native plants are invasive, and not all plants that we call “weeds” are invasive species.
  5. On a signal, one student from each team will race to the other side of the space and “pull” an invasive plant to bring back to their team. The team then decides if they agree with the selection. If they agree, they keep the photo of the plant and send the next member of the team to “weed out” another. If the team does not think the plant pulled is invasive, they will send the same team member back to the table to return the photo. This team member does not get a second chance at choosing a plant, and the turn switches to the next team member.
  6. Play ends when all team members have had a chance to select a plant.
  7. To score, teams count how many invasive plants they collected. If the teams collected any native plants or introduced (but non-invasive) plants, they subtract this number from their score. The team with the highest score wins.
  8. Have partners or small groups discuss the experience and then gather everyone in a group to debrief. What plants did they recognize from the schoolyards, their gardens, or neighbourhoods? Was anyone surprised to discover that certain plants were invasive? What plants did they recognize that were “weeded out”? Share information about a few of the invasives including how they were introduced to BC and their impacts. See the Preparation section for suggestions of species to present to the class.
  9. Share how we can be PlantWise to prevent the introduction and spread of invasive species, such as by not purchasing or planting invasive plants, by disposing of invasive plants properly, by not dumping garden waste, and by sharing what they’ve learned. Remind students that by learning about invasive plants they are well on their way to being PlantWise!
Reflections and Assessment
  • Discuss how they were able to identify the invasive and native plants. What features did you notice that helped you with identification?  What plants “fooled” you or were hard to identify? 
  • What surprised you about this activity? Were there any plants that you didn’t realize were actually invasive? Have students discuss the activity using the I Used to Think…Now I Think thought routine (Project Zero, Harvard Graduate School of Education).
  • Name 3 invasive plants from your region, how they got to BC, and their impacts.
  • Name a way that we can prevent invasive plants from being introduced or spreading in our communities.
Accessibility and Adaptations
  • Play as a “Native Plant Gardening” version where students only collect native plants.
  • If students are not very familiar with plants or as an alternative game, include photos of native, non-native, and invasive animals.
  • Instead of being an active and competitive game, you can play this as a small group, cooperative activity to sort photos into a 2×2 grid of From Here/From Away and Causes Harm/Doesn’t Cause Harm. See the From Here, From Away lesson plan and video synopsis.
Extensions
  • Do research on one of the species included in the game. Where is it native to and how did it arrive in BC? What are its impacts and what people are doing to prevent the spread or manage it? 
  • Take it outside! Go for a walk in the community and see if you can find some of the plants that were in this game. Bring along photos from the game to help you find the matching plant or use Plant Viewers (Coastal-native; Coastal-invasive; Interior/Northern-native; Interior/Northern-invasive). Tally how many native/non-native/invasive plants you find.
  • Make a PlantWise, invasive-free school garden or container planter. Use the Grow Me Instead guide to help you! Adapt the lesson plan Native Plant Garden Planning (Grades 7-9) to your students’ grade level.
Connections to First Peoples’ Perspectives

Many plants that are invasive in BC today are a legacy of colonization. European settlers often brought economically important plants with them or planted ornamentals from their native country to remind them of home. For example, Scotch broom was first brought to BC in 1850 by Captain Walter Colquhoun Grant, a Captain in the British Army and a settler on Vancouver Island, sent by Queen Victoria. Grant planted three Scotch broom seeds on his property in Sooke to remind him of the yellow hillsides in his native Scotland. Scotch broom’s spread continued as it was planted as bank stabilizer during road development, and as discarded crate packing materials for gold camps along the west coast. Today Scotch broom is considered one of the worst invasive species in BC especially as it impacts so many species at risk, including cultural, medicinal, and food plants important to First Nations on Southern Vancouver Island.

Learn more about Scotch broom here and impacts on Indigenous cultural species in this article: Stories of Resilience: Indigenous Approaches to Invasive Species

Additional Resources
  • Aliens Among Us: Invasive Animals and Plants in British Columbia. Alex Von Tol, 2015. Royal BC Museum, Victoria, BC.
  • Grow Me Instead: Native and non-invasive alternatives to the most invasive horticultural plants in BC. (ISCBC)
  • Identify BC Invasive Species, (ISCBC) Searchable webpage on invasive plants and animals in BC.
  • Invasive Species in Seed Mixes (ISCBC article)
  • How To: An Invasive Video Series (ISCBC)
  • Invasive Plant ID Cards (ISCBC) Field ID cards for some common invasive plants in Northern, Interior, and/or Coastal BC and tips on if or how students may remove them.
  • Invasive Species Teaching Cards (ISCBC) Downloadable full-sized (8.5×11”) photographs of invasive species in BC with fun facts on reverse.
  • Nature Out of Balance: How Invasive Species are Changing the Planet. Merrie-Ellen Wilcox, 2021. Orca Book Publishers, Victoria, BC.
  • Outdoor Learning School and Store. A charitable social enterprise offering a wide variety of outdoor learning tools, resources, and training. Check out the Invasive Species Education Kit.
  • Play Your Part: Best Practices to Prevent the Spread of Invasive Species (ISCBC).
  • They’re Here! How Invasive Species are Spoiling our Ecosystems. Roland Smith, 2023. Henry Holt and Company, New York.